My local game store has rows of D&D and Pathfinder books they've definitely overpurchased. For example, at one point they had about 15 copies of Van Richten's Guide to Ravenloft. They also put the date of arrival on their price tags, so you can see that they have been sitting on the shelf for over a year. They'll have a wacky number of supplements, but no core rule books. For example, there's an Investigator's Handbook for Call of Cthulhu, but they don't have the Keeper guide that has all the rules for play. You can get five copies of Pathfinder's premium collector's edition of Fists of the Ruby Phoenix, but there's not a Player Core in sight.
Everything is shrink wrapped and full retail cost. Sometimes they break apart boxed sets (such as the Spelljammer box) and sell the individual books at an increased cost. There's the occasional supplement for something like Everyday Heroes, but it's really nothing I'd want. I have hundreds of dollars in store credit and have difficulty finding anything worth getting for "free."