This website finds books and DVDs worldwide from the least expensive to most expensive as well as the expected postage rates. I am currently a university student and one term I saved $140 off the four text books I needed for that term. I also use it to locate other types of books, including hobbies and novels. Not all books are cheaper from overseas, and it is great to support Australian businesses.
Type in the author's name or book/DVD title and a list appears from where you click to select the store. The page from the online shope appears and you can order from there.