Although there is a way to determine an average cost per square foot for commercial property there are many factors that can come into play and aside from property location and features the terms of the Lease Contract will also effect the cost per square foot.
It would be best to sit with a local realtor who understand commercial real estate and have an analysis of your specific property done for you.

Fran,

It depends on several factors; exact location, zone etc.
If you provide more info on your property, I can help you out a bit more. More info you give, the more accurate I can be since it is tough to do accurate comps on commercial, and I am the commercial person in my office.
Call if you need, or email me back,

John Jelinski
Crossroads Realty, Barnegat
609-713-3454
johnjelinski_7@msn.com