I think it would be a great way to encourage people to start projects and show them off.
I am roughly thinking of submissions sometime in September, with a variety of categories (single small figures, squads, vehicles, single large figures, maybe best conversion).
Prizes would probably just be along the lines of 3D printed statues for any winners willing to send a post address, and a sense of pride and accomplishment.
If there is interest details can be worked out further.
I would not be in for the prize but for the reason to get something painted done. September would be a good time too, i tried to paint last week and my wet palette dries out so fast its unbearable.