Best slot 2 flash and where to buy?

I'm trying to find a slot 2 flash cart with good gba support, preferably with an external memory slot (any size of sd) and fits into a DS Phat. (I've heard m3 is the best, but its crazy expensive. will buy if i have to, but cheaper is better) I recently bought a supercard rumble minisd without realizing it doesn't support gba, which sucked. Royally.

I need it to be compatible with or independent from r4ds too.

And where could I buy whatever you suggest? Please post a link to a store with the item IN STOCK.

I use EZflash 3 in 1 with my DS lite.For DS phat you can get get Supercard SD from dealextreme.Ezflash 3 in 1 is the best check if it supports DS phat