I would also suggest used book stores. Tech books tend not to move, so they are usually cheap. Though somewhat hard to find.

> Being a textbook it's expensive, so you may want to look for
> it used in a college bookstore. There's also a company called Op-Amp
> technical books which sells at a discount. It is worth the money though.
> I have other books which are "standards" in aerodynamics,
> none of which are as readable and understandable as Anderson.