Generally the main acts are the ones who get paid. Other planes and people like private planes is just time donated. Pay varies on the aggreement between the pilot/company and the company orginizing the airshow. However if the air show pilot does not have a commercial license, they can't make profit. (in FAA rules) However I believe all they can get is the cost of fuel.
Good Luck to all Skyway Pilots! It's been great working with you!