To suggest there is an average cost per square foot is also incomplete. The average expectation for one person who has always had laminate counter tops, stock kitchen cabinets and modest carpet will be different from the expectations of someone that has always had granite counter tops, custom kitchen cabinets and exotic hard wood floors. "Average" is in the eye of the beholder.
Consult a reputable Builder to get a real number. Happy to help with that as we offer Architectural Design services, General Contracting and Real Estate services in one office at Modern Rustic Homes. Here are a few links that may be helpful:
Modern Rustic Homes - http://www.ModernRusticHomes.com.
Buy vs. Build Considerations - http://www.modernrustichomes.com/start-finish/
Design/Build Process - http://www.modernrustichomes.com/start-finish/new-homes.aspx
Real Estate Option - http://www.modernrustichomes.com/real-estate/
New Home Construction Option - http://www.modernrustichomes.com/construction/
Hope this helps.
Modern Rustic Homes