You should take a look at what the
Adeptus Windy City group has been doing the past few years. They run an 11-month circuit, after which the top 16 players are invited to play in a final 'best of' event. Each monthly event has a slightly different format and sometimes even a different scoring system.
They charge a small fee for each event ($10-$15 I think) and that money is used to purchase prize support which is randomly raffled off at each monthly event. This stops certain players from dominating the local events and continually claiming a large portion of the prize support - which ultimately is only fun for one person. Additionally, this helps keeps attendance up and gives everyone a fair shot at walking away with something. Your performance at the monthly events earn you points towards the overall rankings, which in turn determine who get an invite to the final event (complete with trophies and all that). I believe only a certain number of your best performances count towards that ranking total, but I might be wrong about that.