This site searches 41 internet booksellers for the best pricing. A quick check of several popular titles like Sixguns by Keith and Hatcher's Notenote shows that a $10 saving is easy and that seller 'A' may have the best price on book 'A' but may not even be close on book 'B'.
http://www.addall.com/

Bye
Jack

Jack,
thanks for this link. I've found a few books that I've been looking to aquire at much more reasonable prices.