[chrisfl]

I haven't done this with my team but for my eagle project I did a carwash and, in 5 hours and made $1000. I had to turn away people too because the venue I was at had an event afterwards. I did another one the next weekend and only made half of that because of a different and smaller venue and bad weather, but people kept asking if it was a weekly event because we were doing a better job than the carwash business in town. Doing weekly carwashes would be a great/practical fundraiser for an FRC team. It just takes putting in the effort and a good venue.
P.s. You can get almost all of the supplies donated from local businesses and car part stores. That's what I did and only had to buy 2 small brushes.