If you are native to the Phoenix area, I'm sure that you have heard of or have been to Bookman's Entertainment Exchange. They have used books, DVD's, CD's, magazines, game systems, etc ... it's my idea of heaven, in a nutshell, being a lover of used and/or vintage things.
However, my favorite thing about Bookman's is their foreign language section. You can find great resources for language learning for pretty much any language, and for extremely cheap prices. Take this past Saturday, for example. I found two extremely rare works in Spanish: One called "El general en su laberinto" by Gabriel García Márquez and another called "Dos Novelas Cortas" by Miguel de Unamuno. The former is a first edition, now out-of-print. How much did I pay? $6! The latter was my favorite purchase of the two, however, because there are extensive footnotes in English and a section in the back of the book for vocabulary and also a list of discussion questions. I had my brother look up the price for this book ($64!), and at Bookman's I paid $3. This language nerd was a happy customer!
So there you go ... go check out the foreign language section at your local used bookstore, because chances are you will find a few gems.