Gameboy Advance and Gameboy Color Game Cartridges. All tested and working.
 
Details/Prices:
 
Gameboy Advance:
Mario Kart Super Circuit - $25
Backyard Baseball - $15
Earthworm Jim - $25
Warioland 4 - $40
Sonic Advance 2 - $30
Frogger's Adventures: Temple of the Frog - $15
 
Gameboy Color:
Tony Hawk's Pro Skater 3 - $10
M&Ms Minis Madness - $10
GEX: Enter the Gecko - $10
Arcade Classic 2: Centipede and Millipede - $12
Frogger - $15
Razor Freestyle Scooter - $10