For us po'folks, $40-$50 and up per game...I got kinda spoiled when I went through a DC buying binge and picked up games for $8 or less.
The more rare ones seem to be, IMO:
-Capcom or Marvel vs. games....hard to find, too.
-Anything driving, like Ducati World Racing Challenge, F355, Sno-Cross, and Super Runabout.
-The bleemcast games have suddenly shot up...dunno why.
-Some of the RPG/Adventure types have gotten expensive too, like Shenmue Limited Edition, Rogue Spear, and Spider-Man.
I think the limited edition version of Sonic Adventure is probably one of the rarest DC games out there, along with Resident Evil 2 and the Namco and Midway classics titles. All this talk has suddenly made me want the ones I need...think I'll go browse around ebay for a bit
.