Life's too short to get bogged down in mail order when a virtual company will do it all for you. High street bookshops are still usually cheaper than the net because online discounts are less than postage. Expect that to change as volumes increase. But for many people who have made a decision to buy, the convenience of online ordering is more important than price. It's already happening.
Books are compact, easy to read, convenient to store, and pleasurable to hold.
But book publishing is heading for a major crisis when it comes to non-fiction, especially for textbooks and reference works. No encyclopaedia can possibly compete with what I already have on my PC for nothing. Encyclopaedias are simply too small. Within eight minutes of logging online he had located lots of vital information about the organization - and even found an aerial colour photo of the campsite. In seconds text and pictures were cut and pasted into his project.