http://www.3mpub.com/
I purchased from this site many years ago, when their ebook formats were primarily PDF & LIT, and they only had maybe 3 authors. Today, I found them while looking for books from a specific author & found that they've greatly expanded. Like Baen, all the books appear to be DRM-free, but they have a wider selection (i.e. not limited to sci-fi). Still only have a few formats, but they've added .PRC now so it should be suitable for Kindle. And all of their ebooks, that I've checked, are priced at $5.00 (US).
Based on some of the other pages on this site I think it's sort of a 'self-publishing' site. It was started by Michael McCollum who's a sci-fi author but as I said, it's not strictly sci-fi any more.
Anyway, I thought some of you might like the site-it's not flashy, but seems to be reasonable about their ebook policy.