My parents picked up what I believe is an Atari brand 2600 style "replacement" joystick. I haven't seen it but from the description (box says something like "for game system 2000 series and Atari 400/800 computers") it sounds like a 2600 stick. It's still in its original packaging, never pulled from the box even though the box has been opened. It still has the price sticker on it from Wal-Mart (like $8.99 or something like that).

I know it may not be worth much, but my parents are now big into selling stuff on eBay and I can't give them a great answer. So I said I'll ask "the experts": you guys.