As part of a publishing experiment, 'The Friday Project', an imprint of Harper Colllins, have released several ebooks at the low, low price in the UK of £2.99 (just under five dollars at the time of writing) and apparently enjoyed such exceptionally high sales they're going to expand and promote the next batch of low-priced books. The details are here
, in an article on The Bookseller website written by Scott Pack, a HarperCollins employee:
"We are always looking for new ways to find readers for our books. As a publisher that specialises in turning web content into books, the dawn of the e-book era is very attractive to us—a format that is closer to the original material than the printed version. E-books represent an opportunity to get our titles, especially our backlist, to a whole new audience. And, perhaps the most compelling reason, we were selling bugger all at full price.
And the results of this experiment (because it is an experiment, not a policy, precedent or fixed price structure)? Our sales have gone through the roof."
Some of the Friday Project ebooks can be found here, on the Waterstones site.