Sam's Club is a division of Walmart. It is the membership club retail format they operate that is like Costco or BJ's Wholesale.
Sam's Club liquidates several different ways. The best choice for the small business to buy excess inventory and returns from Sam's Club is to use one of their private marketplaces. Sam's Club operates two marketplaces: a consumer marketplace where they sell overstock inventory in single unit quantities, and a business to business marketplace where they sell overstock, customer returned, and even refurbished inventory.
One thing to note is that Sam's Club only liquidates small quantities of overstock inventory. The inventory they liquidate is also only overstock...no customer returns. By definition, this is inventory that hasn't sold in their stores, so bear this in mind when you are thinking about what you can sell it for, and how many units you will be able to move, once you buy it.
For a greater selection of product types and condition, but sure to visit the B-Stock Sourcing page to see to largest collection of direct liquidation opportunities accessible to any legitimate business. These are all opportunities to buy directly from the retailers and manufacturers, it is not a liquidator model where you are buying from another third party. Here is a screenshot of the B-Stock Sourcing Network website: