When customers ask us how to determine a price of a book, we tell them to be aware of all the different websites, and listings of all different editions of a book. Prices are not always set in stone when it comes to selling or buying on the Internet. Thousands of used booksellers are selling online, and they use auto price changers that are programmed to usually lower prices on a daily basis. So, always check a price daily, and look at the other major book selling websites. The most popular sites are: Amazon.com, Abebooks.com, Biblio, Ebay, and many more.