YTA. Sorry, I expect downvotes, but giving a 12 year old six weeks to raise $80 is tough. This isn't a console or iPhone he wants, it's to participate in a sport he loves. There are parents who would kill for their kids to show any interest in physical activities.

He's too young to babysit, too young to get a "real" job, and this late in the year, neighbors probably have their gardening needs taken care of. Plus, honestly, I wouldn't want a strange kid I didn't know washing my car when I could take it to the carwash and have it done by professionals for probably the same price.

Pay for his sport and save the money-saving lessons for when he wants something that's strictly for leisure.