I spoke to a few .NET authors who have written their own books. No one writes books for the money because there is not a lot of money in it. Recently, I came across in Amazon a well-known .NET author moving into the e-books category.
Dan Appleman (also known as Daniel Appleman) is a well-known author of Visual Basic titles. He's recently turned his attention to publishing and selling e-books on Amazon. His first e-book title was Hijacking .NET (only 39 pages for $9.95), which was reported in Slashdot com; I am sure he made a killing with that one. His e-books offerings are more focused but have fewer pages than his regular books. Because they are smaller, e-books take much less time to write; as a result, he can produce many more titles. I have discovered at least 13 e-books authored by him versus 12 regular books.
I wonder if he has found a winning formula for making money off of his books. Are the economics of selling e-books more favorable than that of regular books? Since he self-publishes his e-books, the only people who make money off of his books are Amazon and himself. One of his e-books, Regular Expressions in .NET, has a high sales rank of 275 and costs just $14.95. On the other hand, Applenman has written at least one regular book since 2000.