It's pretty hard to get traction through the plugin repository. I offer mine for sale at codecanyon.net. I feel the repository is good for utility plugins, but well-made, premium plugins should definitely be on a marketplace.
I sell a plugin on CodeCanyon as well. They get a big cut from the sale value and the marketplace could have been better but there's no better of its kind so I can't complain. I make around 400usd a month with very little effort.
