I did an on-line search for new homes in Tennessee and found a variety of homes and home styles in different areas. I divided the full price of each home I found by the total square feet and here are examples of what I found. Johnson City $107 per square foot. Jonesborough $98. found that the average cost per square foot was about $113.00. Given the fact that the cost per square foot included the lots, my cost per square foot should be a little less because I already own the lot I'm going to build on.