Most listings are in the $10's per square foot per year. The Madison County submarket is going through a a rise in rates. In the last 3 months, the median rate went up $18 per sqft per year.
In the last 90 days, 2 listings have been made available, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 200% of the office spaces in the Madison County are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,020 sqft. Most buildings in this region are approximately 2 floors. Most buildings in this area were built in 1982 and are Class B.