I haven't really looked at that website, but be aware that some of the R4/M3 cards are quite out of date now, so make sure you do your research and get a current one.

For the record, I have an M3 DS Simply, which I've had for a good 2-3 years now. I don't use the DS that often but so far haven't found any games that I cant eventually get to work on it - but I understand there are some, and likely to get more and more. Again, I'm quite behind on the new releases (most current game I've played is Castlevania Ecclesia).