I came across these people today:
(This happens to be the English language version of the site, but I'd previously looked at the German version, and they have the kind of books I'd be interested in for an ok price):
http://audioteka.com/en/buyers-guide
I'm not interested in the "reading from the cloud" aspect, but what I do like is:
Download audiobooks and listen anywhere
After your payment has been processed your audiobook (with its individual watermark) is ready for download.
You can download it completely or by sections as mp3 files.
Your purchased audiobook is your property and can be download an unlimited number of times.
Which sounds good to me (and I hope and trust it applies to the German site as well).
However, never having heard of them before, I thought it might be good to get some experiences if anyone has used them, or alternative sellers. Thanks in advance.