Here's an interesting quote from artist Nathaniel Stern recently interviewed on iCommons: "I think we need to recognize that it’s not necessarily at odds to both give away the content and sell the object. Art that is in the public interest can be distributed widely, and the same art can be a luxury item for sale."
This applies equally well to books, movies, etc, etc. You can give it away and sell it too. The one is the content and the other is the object. Of course, someone else can come along and sell your content as an object too. But if I am given the choice as a consumer, I will buy the object from the original author, even if it costs a little more. Wouldn't you?