Yes, I have a side project making ~$40k/year doing this in a niche market.

I am fortunate in that I have some volunteers helping me with support so all up I spend about 5-10 hours per week doing support and development work.

In terms of business model, I have been quite generous and provide a perpetual support model for free and paid customers and do not charge for upgrades (currently). As my time has become more limited, I am looking at changing this.

Benefits of this model is that my product is the gold standard in the area and relatively sticky.