How about the bet?
Challenge or cash?
I think cash. More motivation.
Depends on how many participants we get.. 100$-500$?
If we get plenty of participants the 500$ might be a bit too much for someone, although it would be sweet to win like $5k.
If it's a money bet, should there be a start-up fee? like 100$ from everyone that participates. If they quit, no refund.