We then can recycle your book into the national market and pay you the current price the market is paying for that title. The price the national market will pay you for your book is much lower than the price we can pay you when we need the title on our own campus. This is because the warehouse that buys these books must pay for shipping them to a central location, cataloging them, and storing them for months or years before reselling them. These books do not have durable bindings and there is usually little national demand for them as used books. These volumes often make excellent additions to your personal library.
Publishers issue new editions of textbooks frequently.
They do this partly as a result of changing information, but also to discourage the sale of used books. When a new edition of a title comes out, the previous edition loses its value. Old edition textbooks are in surplus in the national used book market, and there is no demand for them. They have no value and unfortunately we cannot buy them. You may wish to keep these books for your own library since they can still serve as valuable references.