Is there a professional service that I can hire to find out for me the fair market price per sqft to lease?

Yes. A quality Commercial Real Estate Broker will give you his/her recommendation for free in hopes of earning your business.

I would check with a certified Appraisal company. They may give your resources for free, or for a fee ask nearby similar property owners themselves. And then coompile the data.
There are compaies that compile this data on a regular basis for many cities/areas.
Years ago I was a residential landlord supplying this sort of information for the company that did the yearly analys.Then as a Realtor, I studied appraisal, while working in a small Realty company that also did appraisals.

I agree with David. A quality real estate broker is always willing to answer your real estate questions. The broker will be an expert in the market and should be able to give you a fair market price per sf for your property.

There is firm by the name of Boxwood Means that can produce a report for you for a reasonable fee (in the range of $100). They specialize in the small commerical property sectors.
Good Luck!