What are some oddly expensive things on ebay/Amazon?

I busted out my dreamcast the other day and I wanted to get Marvel Vs Capcom 2 and Power Stone 2, so I went to amazon expecting to find them for a couple of bucks. MvC2 was $444 (not a typo)!!! I was just curious as to what else might be lying around the house that could make bank on ebay?