I found this site last year and bought about $125 worth of books (33 books), and I just bought some more. They have over 5000 children's books, and thousands of other books. Every thing is super cheap. Most are even cheaper than Amazon. Plus you get free shipping over $14.99, and they have 10% off right now. Most books are in new condition, some have some shelf wear, and most have remainder marks (a small line marked on the bottom of the book). The descriptions tell exactly what condition the books are in. The only bad thing is that they don't have descriptions about what the book is about. I have to go back and forth to Amazon to read descriptions. But it's well worth the trouble with them being so cheap.
http://www.sortfloorbooks.com/And I find it much easier to browse through the subcategory link at the bottom of the browse by category list.
p.s. I don't think they ship internationally, but you could always email them and ask.