Keep an eye on Craigslist and Freecycle. I've given away fabric on Freecycle before, but gotten loads from Craigslist. I think my best haul was a woman doing a serious destash of high-quality yardage for $1 a yard (some were $2) - I brought home over 100 yards. I've also gotten bags of fabric for a song, once with an entire bag full of books and patterns thrown in for free!