Amazon wholesale sellers route inventory through prep centers that receive supplier case packs, apply FNSKU labels, and forward units into FBA warehouses.
Buying wholesale and sending units to Amazon is not a single transaction. It is a routing problem: the brand ships to one address, someone inspects and labels the goods, and a separate shipment goes into FBA under Amazon’s rules. Most independent sellers solve this with a third-party prep center. Here is how the pieces fit together and what to budget.
Why Suppliers Rarely Ship FBA-Ready
Wholesale brands package for retail shelves, not Amazon warehouses. A case pack of 24 units in a plain brown carton meets most distribution needs, but Amazon requires each unit to carry an FNSKU barcode, often needs expiration dates in a specific format, and may reject cartons that exceed weight or dimensional limits. Asking a brand to break case packs, apply your private barcodes, and build mixed shipments is usually a nonstarter.
Claim: Third-party sellers accounted for 62% of all units sold on Amazon. Source: Amazon 2024 SMB Impact Report Date: 2024
That volume runs through a middle layer. Even sellers buying directly from authorized distributors almost always insert a prep step between the supplier and FBA. If you want brands that are already structured for Amazon volume, look at wholesale suppliers that ship in FBA-ready case packs, but expect the majority of your sourcing to require prep.
What a Prep Center Actually Does
A prep center is a small-footprint warehouse that receives your wholesale orders, inspects each unit against your PO, applies the required Amazon labels, performs any bundling or poly-bagging, builds shipments per Amazon’s inbound plan, and hands cartons to UPS or a freight carrier.
Standard services include:
- Receiving inbound freight or parcel shipments from suppliers
- Opening cases and counting units against the PO
- Applying FNSKU labels (and covering manufacturer UPCs if required)
- Poly-bagging items with suffocation warnings
- Bundling multipacks and applying “Sold as set” labels
- Building SPD (small parcel delivery) or LTL pallet shipments
- Uploading tracking into Seller Central
Claim: The US third-party logistics market is projected to generate $349.4B in revenue in 2024. Source: Armstrong & Associates Date: 2024
For a fuller operational walk-through, see how FBA prep centers work for wholesale sellers.
What It Costs
Pricing varies, but the standard model is three line items: receiving, prep, and storage.
- Receiving: typically free for the first carton or two, then $5 to $10 per additional carton. Pallet receiving runs $10 to $25.
- Per-unit prep: $1.00 to $1.80 for standard FBA prep (FNSKU label + basic inspection). Add $0.25 to $0.75 for poly-bagging, bundling, or fragile handling.
- Storage: $0.35 to $0.75 per cubic foot per month, usually only charged if inventory sits longer than 30 days.
Claim: The average FBA fulfillment fee for a small standard item (6 oz or less) was $3.06 in 2024. Source: Amazon FBA fee changes 2024 Date: 2024
Factor prep into your landed cost per unit before you commit to a wholesale PO. A $4 wholesale unit becomes roughly $5.40 landed after $1.20 prep and $0.20 inbound freight share, before Amazon’s fulfillment and referral fees. How pick-and-pack fulfillment pricing is structured breaks down the line items in more detail.
Picking a Prep Center Location
Location affects two things: sales tax and inbound transit time to Amazon’s fulfillment centers.
Sales-tax-free states (Oregon, New Hampshire, Delaware, Montana, Alaska) let you receive wholesale invoices without paying tax that you would otherwise need to recover through resale certificates. For sellers moving six or seven figures a year, this matters.
Transit time to Amazon’s network is the other factor. Amazon’s inbound placement service now assigns multiple destination warehouses per shipment, so a central-US prep center often reduces freight cost per unit compared to a coastal one. West Coast sellers importing from Asia frequently prefer a Los Angeles prep partner to shorten the drayage leg. For context on that choice, see finding an FBA prep and fulfillment partner in Los Angeles.
Claim: Amazon’s FBA inbound placement service fee for standard-size items starts at a minimum of $0.21 per unit. Source: Amazon Seller Central Date: 2024
How to Connect Your Supplier to the Prep Center
The handoff is the step sellers most often get wrong. A clean process looks like this:
- Place the PO with your supplier. Include your prep center’s receiving address as the ship-to.
- Add a reference number (your account ID at the prep center, plus the PO number) on the outside of every carton. Most prep centers reject or quarantine unmarked freight.
- Email the PO to the prep center the same day you place it. They need to know what is coming, how many units, and which SKUs.
- Confirm case-pack structure. Is it 1 unit per case, 12, 24? This drives prep time and whether you need bundling.
- Share your Seller Central shipment plan or ask the prep center to create it on your behalf.
- Approve the outbound shipment once the prep center uploads carton weights and dimensions.
Suppliers you source through structured marketplaces often already carry this information. B2B wholesale platforms that integrate prep and fulfillment can cut the coordination steps down significantly.
Prep Center vs. Doing It Yourself
Some sellers prep in-house, especially early on. A kitchen table, a thermal printer, and a case of poly bags can handle 50 to 100 units a week. Past that, the economics flip.
| Factor | In-House Prep | Third-Party Prep Center |
|---|---|---|
| Per-unit cost | $0.10-$0.30 (labels + bags) | $1.00-$1.80 |
| Labor | Your time | Included |
| Space | Garage or spare room | Theirs |
| Scalability | Caps around 500 units/week | Thousands per week |
| Sales tax exposure | Tied to your state | Tied to prep center state |
| Receiving infrastructure | Residential, limited | Loading dock, forklift |
Claim: Approximately 2 million+ US sellers were active on Amazon in 2024. Source: Marketplace Pulse Date: 2024
The break-even is usually around 300 to 500 units per week. If you are above that and still prepping at home, your hourly rate is probably below minimum wage once you count sourcing, admin, and listing time.
Common Pitfalls and How to Avoid Them
A few patterns show up repeatedly with new wholesale sellers:
- Unbarcoded inventory arriving at FBA. Happens when the prep center misses a SKU or you forgot to create FNSKUs in Seller Central. Always confirm barcodes exist for every ASIN before the outbound ship date.
- Case-pack mismatches. You bought 288 units expecting 12 cases of 24. The supplier shipped 24 cases of 12. Prep time doubles. Confirm case-pack count on the PO, not just total units.
- Missed expiration-date rules. Grocery, supplement, and beauty items need dates printed on both the unit and the outer carton in MM-DD-YYYY format. Check the category requirements before you order.
- No MAP check before buying. If the brand’s MAP is close to Amazon’s current Buy Box price, your margin after fees may not cover prep. Run the math on landed cost + FBA fees + referral fee before placing the PO.
- Ignoring inbound placement fees. Amazon’s 2024 placement service adds cost that sellers often forget to model. Build it into your per-unit math.
Claim: Amazon’s worldwide net sales attributed to third-party seller services reached $140.1B in 2023. Source: Amazon 2023 Annual Report Date: 2023
Putting It Together
If you are buying wholesale for Amazon, your working setup needs four parts: a sourcing channel for brands, a prep center that accepts supplier shipments, a Seller Central workflow for creating FNSKUs and inbound plans, and a landed-cost model that includes every fee before you place a PO. Get those four working together and the operation runs on its own.
Catalist AI connects Amazon sellers with emerging consumer brands and offers FBA prep and fulfillment on the same platform, so sourcing and prep sit in one workflow instead of two vendor relationships. If you are scaling wholesale volume into FBA, Apply to Join and get access to vetted brands and integrated prep in one place.