It's not really that much to bring in. I helped can before football games before Dance Marathon here a couple times, and we usually pulled in about $50-100 per person. Keeping in mind that our Dance Marathon is not nearly as large or well-known as Penn State's, and that we probably had fewer people out canning and for a shorter period of time, I don't think it would be a stretch to bring in $3000 in one weekend.
Give that you could bring in $50-100 per person for two hours' work, I'd say that canning was a little more lucrative than working at McDonald's.
