I dunno, Disgaea used to be really hard to find, but last Christmas (last time I was in the states and shopping) I saw, no shit, at least 50 new, sealed versions. Every Fry's I went to had a bunch, and I saw several at GS.

I actually bought 2 and gave them out as Christmas gifts

Just to pile on the lists a bit -- all the horse sims will be hard to find, G1 Jockey 3 especially. Don't know if they have any real value outside the hardcore horse sim set, but I can guarantee 10 years down the road you'll have a bitch of a time finding them.