Quoted from Pinballmike217:Most of the rare games are rare because they stank and the factory couldn't sell any. Rare DOES NOT always equal valuable. Games like Big Bang Bar and Kingpin are valuable because they are great games. Capcom could have sold thousands of each if they didn't go out of business.
Eh, Kingpin is worth money because rarity and the story behind it. Pinball Magic is the better player, but not as rare and no story so not worth near as much.
Rarity doesn't always mean it was bad. Capcom couldn't sell because of Williams. Alvin G had the same problem and few would argue that mystery castle is a bad game despite its low production run.