Data shows a nationwide average price difference of $22,115. The National Association of Home Builders (NAHB) conducted a construction cost survey in 2015 that breaks down the average costs of construction into 36 categories. Their data shows that the average construction cost of a single-family home was $289,415, and the average size was 2,802 square feet. Compare that to the National Association of Realtors (NAR) data on sales for single-family homes in 2015, which shows a nationwide average sale price of $267,300. Keep in mind, however, that the costs associated with buying homes and building homes vary significantly by geographic location. Homes purchased in the Midwest in 2015 were much lower at an average of $207,100, whereas homes purchased in the West were at an average of $355,000.