Where do you buy audiobooks without DRM?

I love listening to podcasts. And would probably also love to listen to books. But where to buy those? Somehow I have the feeling that the user experience will be dismal and I will get problem ridden DRM monstrosities when I just sign up for the next onlineshop and buy a book.

Any recommendations where I can simply by books as MP3s and not be plagued with anything else?