Cost of the engineer stamp for drawings

Hello,

I am currently working on an outdoor art installation project with a group of people. It is a temporary structure, a dome @30' DIA.

I am recent graduate in Interior Design program and I am the person who did all the drawings. The organizers of the festival are asking us to have our drawings stamped / approved by an engineer. I am just wondering how much would it cost for an engineer to look over the drawings and to stamp them.

We are two small grassroots organisations who are trying to create green art installation so we have a budget for this. If there is any chance anyone can help us we would be very thankful.

Any help is appreciated.