In my experience if you are a pretty good developer and good at communicating, you can find small bits of work without much effort. Now I'm doing a lot of consulting so charge more, but previously I would pick low stress / low mental fatigue projects, with people I enjoy working with (often pre funding prototypes), and charge between $65-$85/hr which could be another $500-600 / month at 2 hours per week.
I also never used any of the freelancing sites, and always found work through personal connections, since it dramatically lowered the risk of getting a bad fit for me.