SourceMogul Finds the Opportunity. Here Is What Happens to Your Margin After the Listing Goes Live.
SourceMogul identifies products where the spread between a retail price and the current Amazon selling price looks profitable after fees. That calculation is useful at the moment you are deciding whether to buy. It is not a guarantee of what you will earn once your units are live at FBA.
The gap between the profit SourceMogul shows and the profit that reaches your account is the problem this guide addresses. Understanding that gap, and closing it with a minimum price floor enforced by a repricer, is the difference between an OA workflow that holds its margin and one that erodes it one sale at a time.
TL;DR: SourceMogul calculates your projected profit before you buy. It does not manage your price once inventory is active on Amazon. A repricer with a Profit Protection floor takes your SourceMogul sourcing cost, accounts for costs SM does not include, and enforces a minimum price on every sale. The result: the margin SourceMogul identified at sourcing is the margin you protect at sale. View integrations.
What SourceMogul shows you, and the one thing it cannot control once your inventory is active
SourceMogul shows you the projected profit on an OA product before you commit to buying. It does not control, monitor, or protect that profit after your inventory goes live on Amazon.
SourceMogul scans retail websites and compares prices to Amazon. For each product it surfaces, you see the retail source price, the current Amazon selling price, an estimated FBA fee, the applicable referral fee percentage, and a projected net profit and ROI figure. That information tells you whether the buy is worth making at today's prices.
What SourceMogul does not do:
It does not watch your listing after you go live. It does not know when a competitor undercuts your price and shifts the Buy Box away from you. It does not respond when the Amazon selling price drops two weeks after your units ship. It does not enforce any lower limit on the price your listing displays.
The moment your inventory checks in at an FBA fulfilment centre, pricing control passes entirely to you or to whatever repricing tool you have set up. A product that looked profitable in SourceMogul's scan window needs a live enforcement mechanism to stay profitable in the Amazon marketplace. SourceMogul provides the intelligence. A repricer provides the enforcement.
The profit gap: why the margin SourceMogul calculates and the margin you receive are often different
SourceMogul's profit estimate is based on what it knows at scan time: the retail source price, the current Amazon price, and estimated fees. Four variables it does not account for regularly reduce the actual margin below the projected figure.
1. Prep and labelling costs
SourceMogul records the product's source price. It does not know what your prep centre charges per unit to poly-bag, bubble-wrap, label, or box your inventory before sending it to FBA. Those costs are fixed and paid before a single unit sells. A prep cost of $0.80 per unit does not sound large. Across 50 units on a product with a $6.00 projected profit, it cuts your total margin by $40.
2. Inbound shipping to FBA
Getting inventory from your prep centre to an Amazon fulfilment centre has a cost. SourceMogul's scan does not include it. A $0.45 per unit inbound shipping cost is another deduction that does not appear in the SourceMogul profit column.
3. FBA fee accuracy
SourceMogul estimates the FBA fee based on product dimensions and weight in its data. The actual fee confirmed by Amazon when the ASIN is processed in Seller Central is the authoritative figure. For standard-size products the difference is often small. For apparel, oversize items, and products where dimensions in retail databases are poorly recorded, the gap between SourceMogul's estimate and Amazon's confirmed fee is larger.
4. Storage fees
SourceMogul's profit calculation does not include the monthly storage cost your inventory accrues while sitting in FBA before it sells. A unit that takes 60 days to sell accumulates two months of storage fees at the applicable rate. A unit with slow velocity in Q4 risks long-term storage fees if it crosses the 365-day threshold.
The combined effect: SourceMogul projects strong ROI. Prep cost, inbound shipping, an FBA fee slightly above estimate, and 45 days of storage later, the actual margin per unit is materially lower. A worked example:
SourceMogul projected profit: $8.00 per unit (ROI 88.9% on $9.00 source price)
Actual prep cost: $0.75
Actual inbound shipping: $0.40
FBA fee increase vs SM estimate: +$0.15
Storage (60-day hold): $0.25
Total uncounted costs: $1.55 per unit
Actual profit at sale price: $6.45 per unit
That $1.55 gap is not a flaw in SourceMogul. It reflects costs that arise after the scan is run. The fix is not a better sourcing tool. It is a repricing floor set from your actual unit economics, not from SourceMogul's projected figure.
How to connect SourceMogul's unit cost data to your Repricer.com minimum price
SourceMogul's cost data gives you the inputs you need for a Profit Protection floor. The connection is direct: adjust for the costs SM does not see, then apply the minimum price formula.
SourceMogul provides:
Source price (your buy cost at the retail site)
Estimated FBA fee
Referral fee percentage for the category
Projected profit at the current Amazon price
To set a Profit Protection floor, you need:
Landed cost (source price + prep fee + inbound shipping per unit)
Confirmed FBA fee (from Seller Central, not SM's estimate)
Storage cost per unit (estimated based on expected sell-through velocity)
Referral fee percentage (confirm by category: SM's figure is typically accurate)
Target margin percentage
The minimum price formula:
Minimum price = (landed cost + FBA fee + storage cost per unit) / (1 − referral fee % − target margin %)
Using the worked example from H2 2 above:
Landed cost: $9.00 + $0.75 + $0.40 = $10.15
Confirmed FBA fee: $3.55
Storage cost: $0.25
Referral fee: 15%
Target margin: 20%
Minimum price = ($10.15 + $3.55 + $0.25) / (1 − 0.15 − 0.20) = $13.95 / 0.65 = $21.46
At the current Amazon price of $24.00, you have $2.54 of pricing headroom above your floor. Your repricer competes in the range of $21.46 to $24.00 (or higher, if you set a ceiling above the current Buy Box price). If a competitor drops to $21.46, your repricer holds at your floor and declines to go lower. The margin SourceMogul identified at sourcing is now enforced at every pricing event.
The full methodology, including how to account for referral fee tiers that shift at price thresholds, is covered in the Repricer.com net margin repricing guide.
The workflow: SourceMogul profit estimate, minimum price formula, floor entered in repricer
The SourceMogul-to-repricer workflow runs in a fixed sequence. Each step builds on the previous one. Getting the sequence right is the difference between protecting the margin SM found and accidentally selling through it.
Step 1: Run the SourceMogul scan
Filter by your minimum ROI threshold, maximum BSR, and maximum seller count. Flag products where SourceMogul's profit projection clears your target after a rough adjustment for prep and shipping (a reliable rule of thumb: add $1.00 to $1.50 per unit to SM's cost figure to account for costs it does not capture, and check whether the buy still looks viable).
Step 2: Confirm the FBA fee in Seller Central
Before any units are sent to FBA, look up the ASIN in the FBA Revenue Calculator in Seller Central. This gives you the confirmed FBA fee. If it differs from SourceMogul's estimate by more than $0.20, use the Seller Central figure in your floor calculation.
Step 3: Calculate your landed cost
Source price + prep fee per unit + inbound shipping per unit. This is the number that goes into the floor formula, not the raw SourceMogul buy cost.
Step 4: Apply the minimum price formula
(Landed cost + confirmed FBA fee + estimated storage per unit) / (1 − referral fee % − target margin %). Set this as your Profit Protection floor in Repricer.com.
Step 5: Set your ceiling
Enter a maximum price in your repricing rule. For a standard OA product in a competitive category, a ceiling 10% to 15% above the current Buy Box price is a reasonable starting point. For seasonal or clearance products with a short demand window, a higher ceiling gives you the option to capture elevated prices when competitors go out of stock.
Step 6: Go live
Your repricer begins monitoring competitor offers from the moment your units are live at FBA. Repricer.com responds to competitive pricing events in under 90 seconds (Repricer.com platform data). Your price moves within your floor and ceiling automatically, without manual intervention between sourcing and sale.
Book a Demo to see Profit Protection configured against a real ASIN in Safe Mode, with no live price changes during the demonstration.
What to check in week one: confirming your repricer floor matches SourceMogul's cost calculation
The first week after going live is the period where floor miscalculation has the most impact. Run three checks to confirm your Profit Protection floor is set correctly before you have sold through significant volume.
Check 1: Compare your first 5 sales to the floor
Look at the price each unit sold at. Were all sales at or above your Profit Protection floor? If a sale occurred below your floor, the repricer is not enforcing the floor correctly or the floor was entered incorrectly. Verify the floor value in your Repricer.com settings against the formula output.
Check 2: Confirm your actual FBA fee against the Seller Central fee
Go to Seller Central, find the orders from your first week, and look at the FBA fulfilment fees charged. Compare these to the fee you used in your floor calculation. A fee higher than your calculation used means your floor is set too low and every sale below the corrected floor is selling at a lower margin than intended. Recalculate and update the floor for the remaining units.
Check 3: Track your actual margin per unit on the first 5 sales
Take your sale price, subtract the actual referral fee charged, the actual FBA fee, and your landed cost. The resulting figure should match or exceed your target profit per unit. If it does not, identify which cost line is higher than your calculation assumed and adjust your floor accordingly.
These three checks take approximately 30 minutes in week one. They are the most efficient way to confirm that your SourceMogul-sourced floor is performing as intended before you source and list more inventory at the same floor setting.
The Repricer.com features page covers how to view Profit Protection performance data across your active ASINs, including which sales triggered the floor and at what price.
When to update your minimum price if your SourceMogul estimate turns out to be off
A repricing floor is not a permanent setting. Four events should trigger a floor review and update: your actual costs changed, Amazon changed its fees, your sell velocity was lower than expected, or SourceMogul's FBA fee estimate was materially wrong.
Your costs changed
If you switch prep centres, your prep fee per unit changes. If your inbound shipping rate changes because you moved to a different distribution model or your carrier costs shifted, your landed cost changes. Either event makes your current floor wrong. Recalculate and update.
Amazon changed its fees
Amazon updates FBA fees and referral fee rates for most categories once a year, typically in January or February, with occasional mid-year adjustments. When fees change, any floor calculated under the old fee schedule is understated. The change is not automatic inside your repricer. You need to recalculate the floor for each affected ASIN and enter the updated figure.
Sell velocity was lower than expected
If a unit sells in 90 days instead of the 45 days you assumed when estimating storage costs, your actual storage cost per unit is higher than the figure used in your floor calculation. On a product with thin margin, 45 extra days of storage per unit across a batch of 30 units adds up. If velocity is consistently slower than the assumption, update your floor to include the higher storage estimate.
SourceMogul's FBA fee estimate was materially wrong
For products where SM's estimated fee and the Seller Central confirmed fee differ by more than $0.50, the floor was set from an inaccurate input. Recalculate from the confirmed fee and update. For products where you find consistent dimension or weight discrepancies between SM's data and Amazon's data, build in a $0.25 to $0.50 buffer above the confirmed fee in future floor calculations for similar products.
Repricing floors are most valuable when they are accurate. An outdated floor either allows sales below your margin threshold or, if set too conservatively, keeps your price above competitive levels and costs you Buy Box time. A quarterly floor review across your active OA catalogue is a reliable minimum cadence for an active FBA arbitrage seller.
Add automated repricing to your SourceMogul workflow. Try Repricer.com free for 14 days. Book a Demo to see Safe Mode running on your listings before any live prices change.
Key Takeaways
SourceMogul calculates projected profit at scan time, using the retail source price, estimated FBA fee, and current Amazon selling price. It does not control what happens to your price or your margin once inventory is active at FBA.
Four costs regularly reduce actual margin below SourceMogul's projection: prep and labelling fees, inbound shipping to FBA, a confirmed FBA fee higher than SM's estimate, and storage fees that accrue while your units wait to sell.
Your repricing floor is calculated from your landed cost, not your SourceMogul source price. Landed cost = source price + prep fee + inbound shipping. This adjusted figure is the only safe input for your Profit Protection floor.
The minimum price formula: (landed cost + confirmed FBA fee + storage cost per unit) / (1 − referral fee % − target margin %).
Run three checks in week one: compare sales to floor, confirm the FBA fee in Seller Central matches your calculation, and calculate actual margin per unit on the first five sales.
Update your floor when your costs change, when Amazon adjusts fees, when sell velocity is materially below your storage estimate, or when SourceMogul's FBA fee estimate was more than $0.50 off the confirmed figure.
Action Plan
For every SourceMogul find, add $1.00 to $1.50 to SM's projected cost before deciding to buy, as a rough adjustment for prep, shipping, and storage. If the product still passes your ROI threshold at the adjusted figure, proceed. If it does not, the margin is thinner than SM's headline number suggests.
Before submitting your FBA shipment, look up the ASIN in the FBA Revenue Calculator in Seller Central. Note the confirmed FBA fee. Use this figure in your Profit Protection floor calculation, not SM's estimate.
Calculate your landed cost: SourceMogul source price + your actual prep fee per unit + your actual inbound shipping per unit. This is your cost input for the floor formula.
Apply the floor formula: (landed cost + confirmed FBA fee + estimated storage per unit) / (1 − referral fee % − target margin %). Enter this figure as your Profit Protection minimum in Repricer.com.
Set your ceiling at 10% to 15% above the current Buy Box price for standard OA products. Adjust upward for seasonal or low-competition ASINs.
Run week-one checks on your first five sales: sale price vs floor, actual FBA fee vs calculation, actual margin per unit vs target.
Schedule a quarterly floor review across your active OA catalogue. Update any floor where costs, fee rates, or actual sell velocity have changed from your original calculation.
Frequently Asked Questions
1. What is SourceMogul?
SourceMogul is an online arbitrage sourcing tool that scans retail websites and compares product prices to Amazon. For each product it identifies, it shows the retail source price, the current Amazon selling price, an estimated FBA fee, the referral fee percentage, and a projected profit and ROI figure. OA sellers use it to find products where the gap between the retail price and the Amazon selling price is large enough to be profitable after fees. SourceMogul is a sourcing decision tool. It does not manage pricing once the sourced inventory is live on Amazon.
2. Do I need a repricer if I use SourceMogul?
Yes. SourceMogul and a repricer address different stages of the OA workflow. SourceMogul helps you decide what to buy. A repricer manages your price after you are live on Amazon, winning you Buy Box time against competing offers and enforcing a minimum price below which you will not sell. Without a repricer, your price is fixed after launch and does not respond when competitors change theirs. The margin SourceMogul identified at sourcing is only protected at sale if a repricer with a Profit Protection floor is in place.
3. How do I connect SourceMogul data to my repricing strategy?
Take the SourceMogul source price for a product and add your actual prep fee and inbound shipping cost per unit. That total is your landed cost. Look up the confirmed FBA fee in Seller Central. Apply the Profit Protection formula: (landed cost + confirmed FBA fee + storage cost per unit) / (1 − referral fee % − target margin %). Enter the result as your Profit Protection minimum in Repricer.com. Your repricer then enforces that floor on every pricing event, regardless of how far competitors drop.
4. How do I set minimum prices based on SourceMogul profit calculations?
Do not use SourceMogul's projected profit directly as your floor input. SM's profit figure assumes the current Amazon price holds and does not account for prep, inbound shipping, or storage. Start from your landed cost (source price + prep + inbound shipping). Add the confirmed FBA fee from Seller Central and an estimated storage cost per unit based on your expected sell velocity. Divide the total by (1 − referral fee % − target margin %). That result is your minimum price. See H2 3 of this guide for a worked example with specific figures.
