I burned some Delta miles @ Christmas, and at kiosk check-in @ IAH, a message popped up they were looking for volunteers. I accepted. Then they asked what amount of $ I will willing to take for the bump. The message very clearly stated that volunteers would be taken in order of the lowest amount one was willing to accept.
That's kind of hard to bid due to the factors of not knowing when the next available flight would be (would it be 2 hours, would it be overnight etc), could I keep my FC seat, etc.
For all info - I put in a bid of $250 for the IAH-ATL leg and it apparently was not accepted as another guy's name was called and I heard the GA talking to him about his alternate flight.
Hopefully UACO doesn't start going that route for VDB.