find a nearby golf course and ask to become a caddy. You spend most your summer their on weekends, working for golfers, and by the end of the summer, you make it rain. REALLY. I got $500 for caddying a few times and I know places that give out MORE. MAKE IT RAIN
Look around your neighborhood especially for seniors who might need help with household/garage chores. I could really use help organizing my pantry, for instance (I don't suppose you live in Wisconsin, do you? Lol!).