The answer is - whatever you are planning for, add about 25 - 50% for change orders. I can pretty much guarantee you that you and or your wife will want additional electrical outlets, data connections, higher end appliances, AC + duct work, changes to the doors and handles, counter tops...etc (you should get the picture). It is ridiculous what it costs to build a house. Believe it or not - electrical will eat you alive.
Building:
Builder's grade $180+ sf (stick to the plan - laminated counter tops, DO NOT add/move electrical (standard 200Amp electrical service), finished drywall, standard molding, hollow doors, standard cabinets, LVL flooring.
Custom $250+ sf - custom cabinets, all of the outlets you will want, good paint job, solid doors, insulation on the inside walls to reduce noise,..etc.
Just went through it 3-years ago - our change orders were close to 30% and we planned on a lot of custom work.
