I'm in. But I agree the contest fee should go towards MW. If anyone wants to donate prizes then that's another thing. The sheer variety would be daunting unless it was broken up into categories ie Vf-0's, Vf-1's,... figures and misc. Put the various modes into each category (fighter, gerwalk, battroid), then let the anonimous entries be judged by poll. With a couple of mods deciding on any prize distribution to avoid the same couple of individuals cleaning up.
Three months is fine, but maybe don't start until after wonderfest.
This is an awesome idea simply because it might push me to actually finish a build instead of stopping halfway and satrting something new.