First post! I made an account just to say this:
My 256mb flash drive can hold 3 n64 games and maybe 10 snes games and I still have maybe 80mb left (the flash drive also has all my school stuff on it, plus the emulators.) Fyi: Both the n64 zelda games were about 32-ish meg and conker's bad fur day is up around 64. All the snes games are under 5.
Don't come and get on my case about emulation, I just want to point out how little memory games take. Unless you plan on spending more than 200 bucks on vc games, I wouldn't bother with a big mem card, just get one big enough to hold save files to take to a friend's house.