It took me a bit of time to figure out how. Blogger isn't as malleable as wordpress, so I was basically looking at hacks. Then I found the advice that I simply use Paypal. And it was good advice. And now it is so.
Paypal makes it super flippinflappin easy. Just click on Merchant Services > Website Payments Standard. They even have a dropdown menu button feature that allows for the specification of desired file format. I already had my paypal account set up to accept payments because of my freelance work. I'm not sure if that's standard or not.
Anyway, you can see the results over on the side bar and on the My Books tab. Go ahead and click around. And if you accidentally purchase a book or two, well... I don't have anything clever to say. I just devoted a full 60 seconds to thinking of a punchline and could come up with nothing but cliches.
Anyway again, to make this post interesting to non-authors I'm going to list some non-author uses for Paypal's direct sales capabilities:
So, I'm predicting that within the next week I'm going to finish the first draft of Vampires of the Plains Book II: Blood Tells True. I recently started revising what I've got, and so far it's looking like it won't take a ton of work. Yay!