Not really, I think I google searched wisconsin (from your location) and “wal-mart craigs list 7000” or something like that 
We had bonus cards issued one year. They were ordered in October. By the end of the year some people been laid off and the mail room kept the overage. Management suspected they had glommed onto them, but since nobody complained of not getting theirs, they got away with it.
I have heard of people going to one Wal-Mart and buying something on sale for $x. Then go to another Wal-Mart where it might be 5X or something (not on sale) and pocket the profit. They will apparently only give you gift cards since you don’t have the receipt. Keep doing this and it could add up.
Mother buys cards for the place that she works and they sell them to raise money. You save some money over the face value buying as a reseller. You charge the face value. Some times it’s from the company the cards are for. Often it’s a distributer that sells you however many of what you want, so you can get 50, 75, or 100 of the the ones you want. She buys them from a California distributer, because the law there protects the purchaser from them taking monthly fees from the cards while they sit around waiting to be sold. The ones on eBay may be someone buying the reseller cards and not charging full face value, or they could be stolen like was noted, and they may prove their legit at Walmart with one or two loaded cards. The less likely is that they have an eccentric family member that gives them thousands in Walmart cards.