Resident Evil 2 and 3 are in low production and high demand, not sure about Code X.
One of the ESPN Basketball games
Top Angler Real Bass Fishing (goes for 35+ on eBay)
Zelda Col. Edition (Not really rare, just high in demand)
Buffy Chaos Bleeds
Bioncle The Game (?)
I've seen a few people bid high on Pokemon Box, and isn't that still avaibile for 9.99?
A few promo items, namingly the Tales of Symphonia pre-order art guide, goes for $30 sometimes on eBay.
That's all I can think of for now.