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
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.