Well if you dont have a DS GET ONE! lol, i love mine. but if you just have a gba then yeah they have some stuff just for gba. look here:
http://eng.supercard.cn/download.htmthese are just the downloads for the software, i used
http://linker4u.com/pp/linker4u.asp to get the actual SuperCard. You could look around for the card that fits what you need though
Ones that just work for gba are ones like: SuperCard SD & MiniSD, Supercard CF, Movie Player (i personally didnt like that one, but to each his own), just look around there are every where. The great thing about it is if you got one of these and you ever got a DS then all youd need to play DS games is a passcard or something similiar.
Each DS game card has a signiture on it, without that the ds wouldnt play it. What the passcard, superpass, all those, all they do is provide that sig. so the ds would read from slot 2, the gba slot. So basically the Supercard is built for gba but
can run on the ds.