Most listings are in the $20's per square foot per year. The Madison submarket is going through a a boost in rates. In the last 3 months, the median rate increased $1 per sqft per year. That's a 3% rise in rent.
In the last 90 days, 50 listings have been posted online, so you'll want to check back regularly for new listings. About 4% of the available leases in the Madison are subleases, so you will probably have to consider a longer term lease. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,560 sqft. Most buildings in this area are around 2 floors. Most buildings in this area were built in 1989 and are Class B.