I work in theatre. We use Craigslist and Freecycle a lot, especially for prop and furniture shopping. We occasionally post under "wanted" if we are looking for something specific. Just in the last few months I have gotten a faux fireplace, an art deco chair, a huge lumber rack, and an old secretary (desk, not person). I have talked my husband into getting rid of dozens of his beer bottles (he is a homebrewer) on Craigslist. You do have to be aware that this is truly a free market and you are on your own.
ETA - and hundreds of beautiful carpet squares that we are using on a set right now came from Craigslist. When we told the guy we were NFP he gave them to us free.