In the mid 2000's I picked up a copy of Baten Kaitos: Something Something Ocean in the $5 bin at Walmart. A couple years ago I sold it for $70. Mediocre game but apparently nerds go crazy for it.
Fun fact: Baten Kaitos is actually the longest speedrun in existence. There's a category in it called 100% where you have to complete the entire game and collect all the shit etc. I don't know the specifics but the general gist of it is there's an item in the game that only appears after you have two weeks of playtime. So you have to leave your console on for two weeks and play the game for hours each day.
I'm a bit of a niche gamer where I tend to stick with open world or RTS games and do a bit of research beforehand, so apart from some extremely low price steam stinkers I got when gifted $100, I don't have many bad games. One I did buy though and regretted was Starfox Adventures. It just has no replay value at all and besides a few space missions just wasn't fun. I don't even remember why it's so bad now but I just know it's bad. Gamecube games seem to be going through the roof now, so if I wait another 20 years, I might get a tidy sum for it.