There are a couple of high-selling authors on TF that established their theme clubs. They build up customer base using TF and then invite people to subscribe for a yearly fee to get access to all of their themes plus the ones to be released. I guess after you reach certain amount of customers such model is much more profitable.
Eg. http://www.themezilla.com/ and here's a link to their TF profile http://themeforest.net/user/OrmanClark
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.
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.
I've contemplated converting some of my custom WP themes to sell on ThemeForest but I didn't think it would be worth the time.
edit: I often wonder if it would be worth it to try to compete with theme clubs. They seem to make a killing on recurring revenue and release a couple of themes a year.