What type of commercial establishment are you looking at? Remember that unlike residential rents, you'll be paying rent on your "usable" areas plus a rental fee on common areas and related costs (which might be stated as a separate rental rate per square foot of your rented area). E.g. you might pay $15/mo p.s.f. for your rented area, plus $11/mo p.s.f (based on the previous square footage) to cover things such as snow removal from the parking lot.
But different rental agreements structure the rents differently; a commercial real estate agent can help guide you through the questions you will have.