Lots of the games mentioned here aren't that rare at all.
I managed to spot these pretty easy in some internet stores:
Lunar Legend
Cima: The Enemy
megaman and bass
R-Type III
Lunar Legend
Sonic Advance
Double Dragon Advance
Breath of Fire
R-Type III: The Third Lightning
Wario Land 4

However I have a hard time finding new versions of these:
Ninja Five-0
Pocky & Rocky & Becky
Car Battler Joe
Tiny Toon Adventure's: Buster's Bad Dream.
ZOE: Fist of Mars
Onimusha Tactics: The Knights of Lodis
Wario Land 4
Sonic Pinball Party. (Allthough you can get it for about 20 bux in a doublepack with Sonic Advance)