Not WallyWorld, but I bought one of the last K-Mart guns. They had a sale on their remaining rifles and my dad didn't own a lever gun, so I picked up a Winchester mdl 94 .30-30 (Ranger, I think it was) for under $250. When was this? 4 or 5 years ago? Something like that. It was a major pain in the ***, the hag behind the counter didn't really know what she was doing and seemed disgusted with the whole transaction.
Except for the price, it was not a good experience. Within a week the store didn't have anything but shotgun shells. I suspect they sent the rest of their inventory somewhere.

Sorry, that's the only story I have. I bought a box of .22LR and one of .380acp at WalMart one time, but that's an even less relevant story probably.