Books are not too expensive, but many books are too long. I don't mean that it's bad for books to be long, but a lot of books have about 50-60 pages worth of real content, and editors and publishers demand that fluff is added because people don't want to pay ~$20 for a 50 page book. But by adding the fluff they did not actually increase the value per dollar, but instead wasted a small amount of their time.