I just found out about this site, where the community of users contributes to creating audiobooks out of public domain books:
Librivox.org
While obviously not as good as professional work, the quality is often surprisingly good.
For those who don't know already,
Project Gutenberg has over 33,000 free ebooks for you to read on your pc, print out, put on your smartphone, Ipad, etc.
Between those two sites you can save on books and audiobooks for works that have their copyright expired.