There is a great article on porfolio.com about Scott Steinberg whose recent book "The Modern Parent's Guide to Kids and Video Games" is generating buzz in the self-publishing world because it is so varied in price.
There is a printed copy from Lulu.com for $17.99, the iBooks, Kindle and Nook versions are $3.99 and he is also offering it for free as a PDF download and as a Sony Reader copy.
His reasoning is broken down into the following ideas:
1. Control - He has creative control, full IP ownership and rapid turnaround. He says: "With digital sales eclipsing print, margins on virtual volumes better, and advances essentially bank loans negotiated at an interent disadvantage, you'll generally get further, faster (and be happier throughout the process) self-funding projects and controlling your own destiny."
2. Freebies to the Public - He feels that books are printed to be read, not to make ton of money. 9 out of 10 books on the market sell less than 1000 copies, but with digital sales eclipsing print sales, he has seen 100,000 downloads of his book. Free books also get your name out there and create a brand. Free books also open more doors for the coveted speaking engagement which increase readership and also sales.
3. Free Publicity - He says "not only is it a way to cement credibility, share your expertise, and potentially put research to added use. It also lets you package your insights in a media-friendly format that makes it possible to more effectively grab public attention and vault your business into the spotlight."