This is one deal not to be missed if you picked up a cheap GB Micro last year. Or if you still have a DS phat and don't have much in the way of a clue about playing GBA homebrew or roms (Public Domain ofcourse! =P)
direct link is http://www.dealextreme.com/details.dx/sku.2734
I found this cart to give the best battery life out of all those I ever tried in my Micro (M3 perfect Mini-sd V1, Supercard mini *this one* and m3 perfect mini-sd v2 *current one*).
Plays tons of gameboy and gameboy colour roms as well via dwedits Goomba Color emulator, same with nes, master system and gamegear among others.
It'll also work on a ds lite, but stick out a bit. It's official as well. Not one of the replicas.