Last Tue, ATL-MCO, the offer was $400 and they were looking for two volunteers. ~1:00 pm flight, guaranteed seat on a ~5:00 pm flight. I didn't need to be in MCO until the following morning, and was staying at an airport area hotel, so I was fine with the offer. Two of us waited as everyone boarded, but ultimately, our seats were not needed. $400 was the starting, and only offer. Several people were willing to volunteer at that, although another guy and I were the first two to the counter.