Well, that roll off was for the one prize and as of know there is no unique prize for on DM.
Do people want prizes to be handed out at each game? Would door prizes be better? One of the things I am going to do is have everyone sign in so we have a record of who and how many people we have come to these. I can use that list to randomly determine who wins the prizes.
Well, I'm thinking obout a prize for each DM since they do have to prepare and put in the extra time. Then I was planninhg on basically drawing names from a hat (or some equivilant) in between sessions and hand out prices that way.