So Amazon has secured a patent for a used ebook sales system. Great! I write a textbook and after 5 editions moved on from a traditional publisher to Amazon (you can take a look). Clearly, the traditional textbook market received a lot of bad press. Books were far to expensive (true, but the public does not understand why), out of date, boring, etc. None of these concerns caused us to escape from the traditional approach. We were simply interested in offering content in a different format – less book and more Internet at a lower price.
Anyway, a used market for an ebook would be a significant problem for ebooks as textbooks. The academic book market works very differently from a trade book or entertainment book market. First, without the need for publishing companies and with the opportunity for anyone to offer a product, there is a great deal of competition. Second, without the book reps visiting the offices of instructors, there is a challenge in instructors even knowing your book exists. There are two consequences of these factors – the market for a given book is much smaller and the selling price is likely to be significantly lower. I would not argue that either factor is a bad thing for consumers who search carefully for quality products.
What I foresee as a problem though is that the total sales for an offering may never grow larger than the initial adoption. Say a couple of instructors pick up a book and the initial semester sales amount to 100 copies. Instead of having the opportunity to sell another 100 copies the next semester, with a used ebook market you might sell 25. With many of these books selling at approximately $10, there will be little incentive to spend the time necessary to generate a quality resource for this market.
On the other hand, Amazon may find a way to provide authors a part of the resale market. Presently, the brick and mortar stores and the used book buyers take all of the money on resales. The original $100 book is returned at $50 and resold at $75. Not a penny goes to the author or the publishing company. This is why the book costs $100 in the first place. This is the only opportunity for the creators of the content to make a sale. This is also why the author or publishing company are falsely blamed for the cost of textbooks. The easy money goes to the store putting the book back on the shelf for $25.
Maybe the author of a $10 ebook will make $2 on a resale. This might be a fair way to compensate the content creator. Else, those who write will be looking around for other outlets not offering an opportunity for resale.