Click on photos to enlarge.

Surfer Surfer on a Wave
6 inch blue foil paper
from model by Jeremy Shafer

Buying Books:

Japanese Books - YesAsia.com
If you know the title or ISBN of the Japanese book you want to buy, you can search for it on YesAsia or just search for Origami and the author's name in their book section.
Their prices are the best that I've found and always includes free shipping.

English Books - Amazon.com
Good prices and orders over $25 include free shipping.

I have found that buying books on Amazon.com saves money and there are even better bargains to be found there if you click on the "New and Used" link on each book's page. Usually the Used Booksellers have a flat shipping rate of $4 and the prices are cheaper than Amazon's already low prices. Ebay has also been great for buying used books, many in better shape than the ones at my local library.