Concrete Mathematics, $47.49 on amazon, $69.99 on retail. Buy used, still cost more than $35.

Can you get a better deal? the answer is yes, even technically, the book is not the same book.

There are publishers in China sign contracts with some big named publishers in US to sell the reprint edition of the book in the mainland China(ONLY). The book Concrete Mathematic is only 49 yuan retail!(less than $7):

There are other famous books reprinted. Introduction to Algorithms, a popular textbook for algorithm, can be bought in China for a fraction of the price. Save big on textbooks for college never bores me.

NOTE: only the cover have Chinese characters, inside are all English.

The reprint might not be the same paper quality as the old one, but I'm buying books for it's contents, not it's "the feel of it's paper turns me on."

It's against the law to buy or sell books like this outside mainland China. But it's ok for you to buy the book in China and bring it to US for your personal use. You can buy those books online from China-Pub. Sadly, you might need a friend who can understand Chinese pretty well to navigate that site with you.