Figuring Out the Basics to sell on eBay and Amazon. Find a reliable wholesaler who offers low enough prices to generate high enough profit margins on resale. Finding the right wholesaler can require an extensive search. Many sellers, Mr. McGrath said, source their products offline, through local wholesalers or flea markets. Comparison shopping can still be done online, using sites like Liquidation.com and eBay, which offer wholesale items in bulk.