Audiobook and Book Exchange, Trade, and Swap Sites

So far I have obtained audiobooks from the following sources:

--CDs as gifts from Family and friends, or bought myself if I really wanted or found on sale
--CDs checked out from the library
--Files borrowed from Overdrive and OneClick Digital through the library
--Files purchased from Amazon
--Files for free from LibriVox (for out-of-copyright works if a professional recording does not exist or is hard to find)
--Even bought one as a file from iTunes once
--Cassettes bought cheap at bookstores, library book sales, and online. I also have a friend who sometimes gives me cassettes.

It's not enough! There are STILL books of which audio recordings were made, near impossible to reasonably obtain! I also have bales of print books I picked up because they were favorites, said by someone somewhere at sometime to be collectible, and so on. Some I might sell, but would actually rather trade for things I want. Hence this question on sites for book and audiobook exchanges, trades, and swaps:

Anyone tried these? How was your experience? Is one site recognized as the best? Thanks.

(Below is a link but I don't know how to make it clickable.)

Audiobook Swapping Sites - Swap, Trade and Share Audiobooks Online | hubpages