eSmarts has done extensive testings on the shopping agents for books and
rated them on a scale of one to five. For new books, eSmarts recommends using two shopping agents, Acses or PriceScan
and mySimon. You should also visit Shopping.com directly - it is excluded from most agents.
Acses - search on many different bookstores to find the best delivered price on up to ten books at a time; the search database is connected to an ISBN database to help eliminate useless results
MX Bookfinder - searches the major collections of used and out of print books
Bestbookbuys - search on fourteen different bookstores; searches are tied in to a ISBN databse to improve results
mySimon -
You can search using title and author. Not as advanced as other searches but includes five discount bookstores not included in Acses or PriceScan.
A1bookmall - good search on five different bookstores for the lowest price on a book