I was watching this show, and a guy found an Atari 2600 with a few common games, and said he could get like $500 for it. No idea where they get these prices. Then again, I'm sure one of us would overvalue something we weren't familiar with if we really didn't know the specifics and just loosely skimmed the Internet.
I've heard of them finding computer terminals and such that sell for way more than the furniture right next to it and not giving it the time of day. :/