Just recently I was lamenting the fact that it's difficult and/or expensive to buy Japanese media in the US (or I guess any non-Japan country). This is still true, but just a week ago or so I discovered that Japanese books can be ordered in the US. From warehouses in the US.
Kinokuniya, one of Japan's largest book retail chains, has apparently been quietly doing some international expanding over the years. In the US, they have store locations in New York, California, Oregon, and Washington state. They also do online ordering and domestic shipping. Their US website is here.
The other day I ordered a textbook for about $55 and another book for about $12. Shipping was $8. Not bad! So if you're in the market for some J-books (they also have Chinese and some English titles, though don't know why you'd want to buy the English books from them), go check it out.
They also have a membership program. I believe signing up for a year is like $20, and then you get discounts on all your purchases. Worth considering if you plan on buying a few books.