thats part of the issue to do any project with a total value over 500 dollars I need a contractor license to the best of my understanding. Based on my research this would be nearly impossible to attain on a limited part time basis and the expense would negate the few hundred here or there.
I have only done work for friends and family, so it's never been an issue for me, limited or no money changes hands.
I guess it depends on the contractors license fees, if you feel you can get more than that a year, it may be worth it, butyou won't know till you actually put feelers out to see what sort of demand there is in your area. The one thing that gets people unstucks is quoting. You have to estimate time taken to do a job, but charge by the hour. If you hit rock, it's going to take longer, some times a LOT longer so you actually loose money, just be careful.
I have a flat top truck that costs about $1,200 per year for registration, then about 200 for insurance. It's not my daily drive, but over a year, it makes me more than what the government and insurance companies want from me, so it's worth while for me, even though it can sit for weeks un-used.