It is hard to say no additional spend, but how about judging based on %age ROI? So someone could spend $10k but must make $100k to equal someone who spends $10 and makes $100? With all inc/exp accounted for. That should encourage people to keep spending to a minimum.
I like this idea.
As for sidebar links, suggest some others.
As for requiring them to disclose before Jan 1st, I was going to leave registration open during the whole contest, although this would obviously give people who started early an advantage.