Definitely check out Amazon JP. I used to order from CDJapan but with shipping it was way more expensive and slower. If you’re in a country with rigorous (and expensive) customs then it’s definitely worth using Amazon as they’ll deal with the process themselves.
I’ve ordered most of mine through amazon. There are several options through US Amazon. I’ve gone through OMGjapan, but you’ll deal with some of the same hang ups from cdjapan with them. Maybe not as bad but I couldnt really say.
Amazon JP almost always has the best price once you consider shipping. You’ll pay the regular street price for the books, minutes the consumption tax!, and shipping (to the US) is very fast and inexpensive.