Abebooks - Advance Book exchange - a consortium of used bookstores across the country that have listed their stock. Search by author, title, keyword & editions.

AddALL  Used and out of print book search - A book shopping search engine that searches several online booksellers for used and out of print books

Amazon

Barnes & Noble

Borders Stores - Find out if a Borders bookstore in your area has a particular title in stock.

Chambal.com - Compares book prices in real time across major booksellers. Search for rare books, audio books, and multiple versions of a title. Search by title/author, ISBN or UPC code.

Ebay - search for out of print and new books

 Book Valuation

Abebooks - Advance Book exchange -  Search by author, title, keyword & editions to determine current selling value.

Bookfinder - search by title or author to determine current selling price of a book.

Ebay - search for current selling price of a book.

What is my old book worth?-A brief six-page guide showing how to determine the value of old books by Anne Killheffer, a senior reference librarian at the Stratford Library Association.