Well, since you asked, here's some honest feedback:
1.) Read biglenr's "advice for theme league creators" thread. It's one of the 3 pinned topics at the very top of this page and gives you a lot of advice.
2.) Stop excluding WIS HOFers and people with more than 3 championships. That's the majority of users on this site - not to mention the people who fill most theme leagues - that you have just excluded. Look at any theme that fills and I guarantee you at least 1/2, probably 3/4 or more, of the owners would be disqualified by your criteria.
3.) Lower the cap. Much lower. Very very few owners play $200M.
The "market" for theme leagues is very competitive. Supply is large, and you have chosen to limit your potential demand to a very very small percentage of WIS users.