Talk to Chop5 to see if he has any chopsodos available to play Japanese Hucards. As mentioned before, your best bet would just get a Japanese Duo or Duo -R as that would be cheaper than getting the cd attachment with a US System 3.0 card. Again, check with Keith Courage to see if he has any refurb units for sale...
I had been looking at some adaptors from db electronics, The PC Henshin so I'll probably grab one of those along with the GrafxBooster when it's for sale to help save a bit on shipping.
I think the best course of action is to work through the Hu Cards and find the ones I want to own the physical copies of, I'm not out to own every game as I know they'll be ones I wont play so no point owning them, after that I'll look to the CD games and a Duo.
A few more games have just turned up as I type so I've got a good few to go at before I think about buying more.
So far the collection stands at 9 games, I bought these with the console:
Blazing Lazers
J.J. and Jeff
Cratermaze
Alien Crush
Legendary Axe
These just turned up:
Vigilante
Galaga '90
Ninja Spirit
Dragon Spirit
I've just about completed Blazing Lazers, although I'm sure I read about a code you can input to change the difficulty settings???
Legendary Axe is kicking my arse a bit but it's really enjoyable.
I've not put that much time into the others but I think J.J and Jeff could be good with some perseverance, Cratermaze seems a bit easy but I get the feeling there's more to the game than I realise. Either that or it'll end up being a bit dull.