Most listings are in the $10's per square foot per year. The Madison submarket is seeing a decline in rates. In the last 3 months, the median rate fell $3 per sqft per year. That's a 12% decrease in rent.
In the last 90 days, 23 listings have been made available, which means new availabilities are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 4% of the office spaces in the Madison are subleases, so you will probably need to consider the implications of signing a direct lease with the building. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,000 sqft. Most buildings in this area are around 1 stories. Most buildings in this market were built in 2005 and are Class B.