I got Super Metroid for the SNES for free. The video-game renting place was stocking up on new-fangled N64 stuff and I was pretty much the only guy renting SNES games, Super Metroid particularly (no one else was renting it apparently). The shop owner gave it to me one day, was pretty much one of the most awesome presents ever.
I also bought Ogre Battle 64 recently for 2 bucks.