Thanks for this post. The timing is just about perfect. I’m working on a Premium Plugin and had just written some custom code to implement update notifications, but wasn’t happy with it. It shows up on the plugin page, but not at the top or in the counter.

I’ll have a look at your implementation.

Regarding the Free in the repository and premium for sale, the folks at WordPress recently made announcements to discourage this. Encouraging more high quality free plugins and less using the repository as a place to advertise your for-sale products.