It didn't sound like you wanted to do facepainting... are there others doing it at this event?  In a busy day of face painting, I personally made $99 at $1/face.  I usually use acrylic paints and stay away from the eyes and mouth.  I never cover the whole face, just designs.  I also do hands... sometimes the little kids who are shy would rather have something painted on their hand than their face.  If it was summer time, you could do the same thing as "temporary tattoos" and do arms and legs.