For a place that is starting off I would think your prices would be modest. One catch would be that you would have to use thier hose or drive to a car wash with thier car, dry it there and when you come back you can spot rinse it where dirt may have picked up on the rear quater panels.
I am sure people are not going to expect you to have a full blown pressure washer within your first 6 months of detailing.
Just my .02
