why there is currently money in used books

Taking a Second Look at the Nook - PCWorld: "One example of how e-reading could be a lot better: Every major e-reader on every platform remains surprisingly text-centric. Images are an afterthought when they're there at all, which means that a substantial percentage of the world's most interesting dead-tree books can't yet be replicated in electronic form form. The first e-reading software that fixes that is going to have a major competitive advantage for a while."