There are many factors that are considered when a commercial building is being erected. The location, size, zoning and the local economy. In this market, your best bet is to talk with a few local contractors and get a feel for what they are willing to do for you. There are many incentives that are not included in the PSF, you may pay more with one builder but receive more for you money. There is the Marshall and Swift book that is used to determine a price per square foot but in the past the book has been slow to keep up the economy. Now, with the market on a downward slide, the book may be closer to the actual cost. Do your research and you maybe surprised what you find.