I've ordered off of amazon.jp before. I ordered a couple of cds from there a good while back. I bought Do the Box by Do As Infinity through them too. The shipping seems to be a bit more affordalbe than say, cdjapan, but, that's only because the S&H is already included with the price.
You could try HMV too, they're pretty good as well. Nice of you to offer to order stuff for people, though. I'd ask you to order something for me, but, I haven't the cash at the moment to buy much of anything...nothing "anime" wise, anyway (cds are a whole different matter, though). Curse thee bills!