The store will pay cash for most items: RPG books, boardgames, Magic cards, even comic books (but very little). The two things we will not pay cash for are Pokemon cards and Yu Gi Oh cards. The reason for this dates back to the first time Pokemon got hot in the late 1990s. We had a lot, I mean a LOT, of people bringing us Pokemon collections to sell. Many of these people obviously had no idea what Pokemon was, how to play the game, or even how to read one of the cards. They just knew that the cards were popular and a lot of them were worth a lot of money and wanted to know how much we would pay for them.
After a bit, we started worrying about the possibility of the store receiving stolen property so decided to stop offering cash for Pokemon cards and instead only offering trade. We figured that the people who really played the game would happily trade their old cards for store credit they could use to get new or different ones while people who might have stolen cards in the hopes of selling them would not want the store credit. Time proved us correct as the number of people who obviously knew nothing about the cards they wanted to sell dropped off to nearly zero. When Yu Gi Oh! hit big in the early 2000s, we noticed a similar trend in people coming in wanting to sell collections who obviously again knew nothing about the game, so we quickly extended the "Trade Only" policy to Yu Gi Oh!
Surprisingly, at least to us, we have never had that big a problem with stolen Magic cards coming through here. I would hazard that Magic has never entered the public zeitgeist to the level that Pokemon and Yu Gi Oh have. We have never had people lined up 12 deep waiting to get into the store to get a promotional Magic card they way they have for Pokemon and I am still waiting for MDonald's to release promotional Magic cards the way they did promotional Yu Gi Oh! cards.