Yeah, that's do able. You need to find basically 1 client and hope they're pretty decent. Try services like toptal.com, grouptalent.com etc. The high end type ones are best: search HN for more of them. Tell them your time commitment.
Alternatively look on craigslist.
Make sure you have a good portfolio before you start looking: build some stuff to show off.
I don't have a revenue target in mind. If I get at least $25 per hour I spend, I'm more than happy. I have no idea what the market rates are though. I am handy with most technology, and have enough equipment at my disposal.