In need of GBA Flash cart for GBM

[Rotheit]

I need a good, cheap flash cart for the gameboy micro any ideas? I would prefer that it doesnt stick out.

[DanTheManMS]

You've got a couple of options:
1. A traditional NOR-based flashcart like the Flash2Advance Ultra etc. These would have the maximum GBA compatibility, but they are expensive as heck and they take forever to write to. I have one myself, but I probably wouldn't recommend one for casual usage.
2. A CF/SD/miniSD adapter like the Supercard (not Rumble) or M3 Perfect (not Pro) - you'll probably want miniSD as those sit flush within a GBA. While the Supercard is cheaper than the M3, the M3 has higher GBA compatibility. Check out a few compatibility lists before buying to make sure you'll be satisfied with the purchase.