Just a reminder, but
Downpour has audiobooks for rent and is currently
running a sale for up to 75% off the rental rates. During the sale, many books are priced at $1.74 each.
Granted, their catalog is small (~18,000 titles) but if you find something you want to read and don't care if you own it, then you can save quite a bit.
See this post for further details about the program.