Does anyone know if you can use Costco or Sam,s club as an official wholesale supplier?
No, unfortunately. Amazon will not accept these retailers as a proof of having a valid supply chain. Their receipts would be rejected in case you submit them as the proof of authenticity.
You will need to purchase your items directly from manufacturers or authorized distributors who will provide you valid invoices.
Costco and Sam’s offer lots of products to consumers. They do not have a vetting process like manufacturers and authorized distributors do. The only requirements that a wholesale club has is that you need to be able to fog a mirror and you need to give them money for the annual membership.
Most manufacturers offer a warranty on items that are purchased directly from them or through an authorized distributor, such as Sam’s or Costco. Once you purchase that item in the supply chain, you are entitled to the benefits of that warranty. You are the last link in the chain.
If you sell the product to someone else, that is considered to be outside of the supply chain and the item can no longer be considered “New”.
For you to turn around and sell that product as “New” on Amazon, is a violation of Amazon policy.
This is why receipts are not accepted by Amazon and why wholesale clubs are not valid wholesale suppliers.
I don’t recommend it … but actually I have seen sellers cleared in several instances using these sources, when the account was set up correctly and they weren’t just buying retail.