Amazon has a way of listing books such as to hide the cheaper books.
Here's an example of a book I was looking up today. The book is Essential Tibetan Buddhism, by Robert A. F. Thurman.
I did a search on Amazon "Thurman Essential Tibetan Buddhism" and got the following page: http://www.amazon.com/s/ref=nb_ss?url=search-alias%3Dstripbooks&field-keywords=thurman+essential+tibetan+buddhism&x=0&y=0
If the listing has not changed since I posted this, you will see that the lowest-priced book of this title is a paperback edition for $1.65.
However, if you click on the label "Other Editions: Hardcover" at the end of that listing, you will see that you can buy the new hardback edition for only 11 cents!
So, when you are looking for used books on Amazon, be sure to check the "Other Editions" tag attached to some of the listings.
So far, I've not been able to determine what the logic is in how they decide what editions to hide, except that it seems to be the lowest-priced one.
