Half Price Books is one of my favorite stores. I love Borders as well, but they don't sell used books. Since I have no interest in the current embodiment of D&D, Borders doesn't have much to offer me, gaming-wise, apart from WotC miniatures (which, notably, Half Price Books does not sell). Half Price, on the other hand, has a decent selection of used RPG stuff and I've found some real gems there.
remaindered book). Forbidden Kingdoms by OtherWorld Creations, in the Pittsburgh area at least, was on sale for $3.00 (original price: $40.00). It's a neat little book (literally, it's 9.5 in. x 7.5 in) that details a cool system for Pulp Adventures. It's based on the 3.0 rule set, as it was made before the release of d20 Modern. As such, it has more in common with D&D than those rules. For my simple-mind, that is a good thing. In other words, you could play some Indiana Jones-style games based on the D&D rule set. As another bonus, its psionics system is well-regarded, so I might use it as a resource if I'm ever crazy enough to put psionics in my D&D campaign.
Half Price has another remaindered d20 book on sale: the Bestiary of Loerem for the Sovereign Stone campaign setting. This book was $3.00 when I bought it, but I later saw it for $2.00. I believe this originally retailed for $40 or so as well (I'm not certain as the original price isn't published on the book cover). Quite frankly, this book is barely worth the $3.00 I paid for it. The art and product values are great (although barely any of the interior art is by Larry Elmore, despite the Sovereign Stone books being labeled as "Elmore's Sovereign Stone"), but the monsters are just plain boring.
Half Price had quite a lot a copies of both of these books. If you live near a store, pick up Forbidden Kingdoms if you can. Take a gander at the Bestiary of Loerem and judge for yourself. Oh, just a heads up, both of these books were not in the gaming section, but were stacked out on the middle tables with the other remaindered books.