I'll toss this out there. I am a software guy who manufactures a simple electronic device on the side

The product cost around $30k to develop plus around eight months of full-time development effort. We currently make about $15k-20k a year in profits. I've been doing this for six years now, and we make small incremental improvements every release that don't cost a lot to do. I mostly focus on overseeing manufacturing, QA and maintaining a dealer network who will sell the product.

I am embarrassed to say I haven't spent a lot of time on growing the operation, but on the flipside the return is pretty good for the amount of work that I put in to it.