I did, however, make an unpleasant discovery. Diesel, the e-book store, has closed. It seems to have happened around March this year.
I can't say I used it, usually preferring Amazon and sometimes Smashwords, but it's depressing when a bookstore goes under. More competition in the marketplace is a good a thing.
As well as the other retailers listed on my Books tab (Barnes & Noble, iTunes, Kobo, Versent Books and Inktera) it's also well worth checking Abebooks. It's not so much a store as a marketplace for new and second hand books. I've used it a few times, and got a second hand copy of Philippe Contamine's War in the Middle Ages for less than half the cost of a new version.
Speaking of competitive pricing, Malevolence: Tales from Beyond the Veil, is likely to come out within the next couple of weeks. If you pre-order via the publisher's website you can not only enjoy the devastatingly delightful writing (including my short story, Saxon & Khan) that much sooner, you can enjoy getting it for less than the standard retail price as well.