LibriVox and Ebay
All LibriVox files are in the public domain, which means we relinquish all rights to the files. So anyone may use them for any purpose, including commercial uses, such as selling on !Ebay.
We do prefer that people acknowledge that these are LibriVox files, but we can't and don't enforce that (public domain means people don't have to acknowledge us).
Finally, the Ebayers are actually providing a service we can't: distributing our audio on CDs... and we suspect few of them are getting rich on LibriVox. There is competition among them which keeps the prices down.