It was a desktop app that was based on top of XULRunner and yes it was for profit and people payed for it. I have no experience with selling extensions but I wo

It was a desktop app that was based on top of XULRunner and yes it was for profit and people payed for it. I have no experience with selling extensions but I would imagine it is a very hard market to crack unless it is targeted towards enterprise customers. Based on my experience, I can only advise not to base your entire business model on browser extensions as you will become dependent on platform moves (again unless enterprise).