Wow what's happening here? Bad timing for the OP I guess, seeing as people would have answered the question anyo ther day...
Anyways, I'll point towards this page
http://dsdatabase.org/forum/viewforum.php?f=36 of my site as well as the reviews tab at the top of this site, for some detailed information.
Quick lowdown on the carts are:
CycloDS Evolution is the best but costs a ton, the next on the list is Supercard DS ONE, shares similar features, half the price, but a slow GUI and pretty unfriendly.
Then you get recommendation of EDGE or the AceKard 2, EDGE being sturdier, but AceKard 2 being fancier, both really reliable.
Then finally the EZV and the DSTT, probably not the best choices, but you might want to consider it.