If I had any money I would have done this already. One guy puts up a page in the exhibition section for the contest. The contestants make their own exhibition page tutorials (this is the point of the contest) and can provide a link to it in the contest page.
After a month the god members can pm the OP with their top three choices. Then the OP will get the winner's address and contact the vendors, or just send his own prize.
The only rule would be that it has to be something new, not already posted in the exhibition.