The single K-Mart in my city has sold used games for the past 12 years
Same here, I think all K-Marts do. I don't know about walmart (closest one is 15-20 miles away) but I will certainly check next time we go out that way out of curiosity.
My local K-Mart doesn't have used games, but that place is a freaking ghost town, I have no idea how it stays in business. You can get collector's editions that are literally years old for a steal, though.
"'Grab the guns!' 'What about the troll?' 'Leave the troll.'"--ATHF