I am part of a regional history museum with exhibition space of about 6,000 square feet.  We are planning a full gallery renovation, and have received a commissioned conceptual plan for the design that we are pleased with.  We are now in the next phase that involves choosing a company to help construct the exhibit, which includes designing the detailed layout and schematics, building walls and cases, identifying and preparing graphics, designing exhibit mounts, researching and writing label copy, interactive videos and dioramas, and replacing wall and floor coverings.  We have one cost estimate for the entire plan, but I am beginning the research phase of costing the exhibit out. The question I pose to the listserv is:  Is there an industry accepted "per square foot cost" for exhibits of this size and nature?  I welcome suggestions from anyone who has experience in this area.