Theme clubs? Are those the places where you pay a subscription fee to be in a limited club of people that get a new theme every couple weeks?
In general people spend a lot of money on themes. I think you might be better off competing with themeforest or more likely, any of the number of bootstrap theme website popping up.
There a few but elegantthemes.com is one that comes to mind.
You pay yearly to access to a bunch of quality themes. They pay out 50% commissions (and on renewals too) to affiliates but they have 200k+ plus users. They have to bring in a couple million a year.
I believe they started out at much lower prices and started raising it as they released more and more themes.
In general people spend a lot of money on themes. I think you might be better off competing with themeforest or more likely, any of the number of bootstrap theme website popping up.