I braved the frigid temperatures and went to the Half Price Bookstore during my lunch break today. In the past, there I have found near-mint copies of Mordenkainen's Fantastic Adventure ($7), The C&C core books ($9 each), and a ton of old Dragon magazines.
Today I was able to replace my missing copy of the Moldvay Basic rulebook for $5. This sucker is also in near-mint as the pages haven't even yellowed much.
In addition to this fabulous find, they were selling comics in bulk - 20 for $5. I landed a bunch of 70s/early 80s issues of Avengers, Hulk, Iron Man, and Invaders.
Man, I love HPB. :)