Amazon's "used & new" service has been a great help in this. I've found it very useful - and incrediibly inexpensive. Usually the mailing costs are about twice the price of the book. And occasionally the fact that they just link you to some actual seller provides funny coincidences. For example, yesterday I got the copy of prof. Carol Siegel's (of whose work I'm a big fan) excellent "Male Masochism. Modern Revisions of the Story of Love", which I bought as a _mint condition hardcover_ for just $5.98. What was strange that this academic treatise on masochism in literature was sold to me by a U.S. bookstore called "Jessica's Biscuit Cookbooks"! I wonder what else they have in store. (By the way, the service I got from them was /excellent/. The book arrived very fast, in perfect condition, safely packaged in completely recyclable material, in an envelope thin enough to fit through my mail box. All one can ask for in a mail order book store, really.)
Now all I hope is that I actually have time to read all I've bought /and/ actually write something at the same time. But so far there have been no problems - things are looking good.