Blackwell’s, a British bookseller, is randomly selling new paperback copies of ¿Por qué? 101 Questions about Spanish for only $14.62, including shipping to the U.S. This is a great deal as the list price is $32.96. I have verified with Blackwell’s that these are in fact new books, not secondhand.
So if you have been thinking of buying a copy for yourself, or already have a copy but want to give one to your favorite Spanish teacher or hispanophile, now is the time.