Once found a copy of Tony Hawk's Pro Skater 2 for the PC for only a buck.
Other gr8 finds (not recently, but altogether):
* N64, A/V cable and power supply included, no games or controllers - $3
* Fallout and Rainbow 6 for the PC - $a few each
* Some various Rainbow 6-related stuff for the PC (an expansion, Rogue Spear, and some other stuff) - $3 each
* Legend of Zelda (gold cart), Dragon Warrior, Dr. Mario, and a few other NES games (all cart only)- $1 each
* You Don't Know Jack Volumes 2 (empty case

), Volume 3, and Volume 4 - $a couple each
* Harry Potter and the Sorcerer's Stone for the PC - $same as above
* Street Fighter the Movie for the Saturn CIB w/ a "Fighting Vipers" disc inside - $2, I think
* Some books - $1 or less for paperbacks
* Carmen Sandiego board game - $1
* old version of Trivial Pursuit - $1
* Tiger R-Zone SuperScreen w/ Toshinden game - $1-2
* some old comics (Double Dragon, every ish except for #1, and a random issue of Robin) - $3 each, but the wrote the price right on the covers, though their quality probably wasn't worth that much, but it was for a good cause
Also, most, if not all, of the PC games have been with their original jewel case (case might have been imperfect) and most of it's original papers.
Also, the two thrift stores in my area, which are both about 10 minutes away by car, don't usually have a lot of video games. You might be able to find an old PC game, though.
Also, at this one "estate sale", where they were selling off stuff from people's storage sheds (it was a public storage facility, and they sold off stuff from people who couldn't keep paying), and I scored this one thing almost CIB that had Worms: Armageddon (w/ manual), Civilization 2 Gold Edition (w/ manuals) and the manual for Mechwarrior 2, though the game itself was missing. That was a couple of bucks, and two Schwartzenegger DVDs (T3 and Commando) for $2 each.
I once found GTA 1 and Warcraft 1, CIB I think, but opted not to get them. I mean, GTA 1 is free now and Warcraft 1 isn't much compared to Warcraft 2.