I think you should read/watch the following 2 resources if you can:

    'Start Small, Stay Small A Developer’s Guide to Launching a Startup' [0]
    'Creating and selling a digital product' [1]

Your product on codecanyon appears to be doing quite well and has good reviews/sales [2] so you should probably market it more (if you're not doing so already). Also, building an ecosystem of free/paid plugins around it might be something you could explore. Finally, you could look into offering hosted instances for less technical savy users.

Good luck and keep up the good work!

    [0] https://www.amazon.com/Start-Small-Stay-Developers-Launching/dp/0615373968

    [1] https://www.pluralsight.com/courses/creating-selling-digital-product
    
    [2] http://codecanyon.net/item/stock-awesome-inventory-system-and-stock-control/11210315?s_rank=2