Founder @MagikPress, Lead Web Dev @Winculum. WordPress Developer, UI/UX hacker, Free Software activist, Doctor Who Fan, and all-around geek.
One of the most sucessful models for premium plugins is to offer a core plugin for free then allow installing add-ons. These premium add-ons could be created by you or the community. For successful examples, see Easy Digital Downloads, Ninja Forms and Woocommerce.