I was just cleaning out some of my old stuff and came across a few other things to recommend. If you love books the way I do (my husband had to drag me away from a dusty old 8-volume set of Mark Twain at a garage sale yesterday...), then here are some catalogs for you:

Oxford University Press - good prices on hardbound "classics" and school type sets, like Shakespeare, Jane Austin, etc. http://www.oup-usa.org or 800-230-3242.

Dover Publications - low priced paperback classics, many $1 titles. They have a specialty catalog just for kids full of interesting historical sticker books, paper dolls, build-your-own pyramids and classic greek temples from paper cutouts, mazes, etc. http://www.doverpublications.com .

I also want to emphasize what great stuff the Rainbow Resources catalog and the Scholastic book catalogs have, too. I have extra copies of Rainbow Resources old catalogs if you want to take a look. I get tons of Scholastic catalogs (starting in August for the next school year). I also have some back issues of Home Education magazine. Let me know if you want to take a look at any of them.

I can relate to the dusty old books at the garage sale, only my husband wouldn't have been pulling me away.  We both suffer from the addiction, and so far we haven't been able to find a twelve step program for it.
-Kari