It depends on the type of home. If you're going for a simple rambler with average finishes, $100-125 a sq ft is about right. If you want hardwood floors, high ceilings, 3+ stories, large windows, granite counters... it could be double that without even getting extravagent. I have 2 fabulous builders I could recommend in that area, depending on the type of home you were planning. I also have lots of tips for keeping costs down.
Not sure exactly where you own land, but I lived for a while on Bull Run Mtn as a kid, so I know that area pretty well. Give me a call for more information. 703.669.3142 VChrisner@KW.com