Best Book store IN THE WORLD is the Astrology Center of America
The Proprietor is Dave Roell. He has blogs, and a newsletter, and more information about astrology and the books of it packed into his site than you can imagine.
Go there! Its like visiting an on-line flea market of enormous proportion. If there was a BIG CHICKEN BARN for astrology books in real life(for those of you who have visited it in Maine near Ellsworth) it would be Dave's site.
If you have a question about a book, Dave will tell you what he thinks, and even if he sells it, and he thinks its trash, he'll tell you that. Dave pulls no punches.
Its hard to find a really honest guy around, but Dave is IT!
I've known him for years. Don't buy your book from Amazon unless Dave doesn't have it. And if he doesn't have it, and you found it on ebay, he'll even tell you if its a good deal.