I've had okay luck giving things away for free on FBM, I've had decent experiences buying, but not much luck selling.

Latest episode was a good running 9hp briggs Generator engine for free that I put on there....oh boy. Instant feeding frenzy.
The whole world beat my door down it seemed, until it disappeared from the driveway.
It took about 30 minutes.

Before that I listed the toolboxes and ladder rack from this beast for $500 or best offer. Man, the messenger BLEW UP!!
Folks from as far away as Kentucky 'REALLY WANTED IT BAD' (they said in a phone call).
Then about a month went by, and no sale.
I dropped the price to $400. Still nothing, for several days.
Finally someone came and gave a deposit, so I removed it all.
there it sat for another 2-3 weeks until the guy finally showed up to get it.

I wanted a set of 18" wheels instead of the 17's shown in the pic.
Found a set for $100. When I got ahold of the guy he was overjoyed. Nobody showed any interest.
He was so darn happy to get rid of them and get a few dollars he dropped the price to $60 before I could even
set up a time to go pick them up. I didn't ask him to lower the price but that was pretty cool.