I was looking for a cheap shipping option too. I asked my friend who lived there for a few years and then taught Japanese in the USA when she moved back. She used Sasuga for all her teaching materials and said that they were nice and that she never had problems. I just checked by putting 1 item in a cart and they wanted $5 for US Priority Mail. $40+ orders have free US Media Mail.

http://www.sasugabooks.com/

I have not used them, but maybe they will have what you need.

BillJ