Dollars per square foot is only one measure of value, and not always reliable. The quickest answer to your question would be for you to search the address you are interested in at Zillow.com. Realize, Zillow does not guarantee the accuracy of their information and may be as much as 20% off in either direction, but they give you a place to start.
For the best idea of a homeâ€™s value, have a local agent do a comprehensive CMA (Comparative Market Analysis). Good luck with your purchase.