I am a tightwad. It's true. No denying it. And homeschool is no exception. I don't buy what I can get for free, whether it's from the library or online. Here are my favorite places to get free audio schooling:
ESV Audio Bible - totally free. We use this to help us memorize scripture. (scroll to bottom of page)
Librivox.org and Books Should Be Free.com - Gobs of free books from the public domain. Think: classic literature.
Blue Behemoth - trustworthy, downloadable audio and video content for the Christian family. One or two free downloads daily.
Christian Audio - a new free book download offered every month.
My Audio School - classic books, old-time radio theater, historical radio, and television broadcasts; all organized by time period.