I was going to say, you can look at Cael's guide of buying things from Japan. It's really useful and talks about J360s as well, but he kinda beat me to the punch. XD
I guess on a personal level, I got my J360 back in December from play-asia: The slim 250GB 360. It's been really good, I rarely switch it out for my NA 360 unless I'm playing something that for some reason doesn't work (The copy of RE5 I have doesn't work, but I think it's a "defective" copy that just works on my 360 because it just uses the CD to boot the game that's on the hard drive).
Play-asia has a compatibility guide with the games, and it's worth a check out before you go buy a game or something.
For the customs, at least I know I had to pay some sort of fee
I hope I don't have to for im@s 2 >: when they delivered it to my door (at least my dad did), so it might depend on the country and the customs office.
Edit: ahh yes, tweeny had
this problem before even getting her 360. So, hope that customs don't delay your getting???