I bought international editions of Rudin's Principles of Mathematical Analysis ("Baby Rudin"), Artin's Algebra, and Munkres' Topology. The savings were huge, all were the most recent editions, and the content and pagination were identical to the U.S. versions. But Munkres was printed on something closer to toilet paper than what you usually find in books (Artin and Rudin were ok quality paperbacks), and it's also illegal for people living outside some Asian countries to buy Munkres. Not sure about the legality of Artin or Rudin, but I expect a lot of these books can't legally be bought by people living in any of the developed countries. I think they're great bargains, even if printed on really cheap paper, and you're more likely to be hit by a meteor than be prosecuted for buying a black market science book. But maybe you're more moral than me...