The typical asking rate per listing is in the $30's per square foot per year. The Mount Kisco region is experiencing a a boost in rates. In the last 3 months, the median rate went up $4 per sqft per year. That's a 12% increase in rent.
In the last 90 days, 3 listings have been posted online, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,800 sqft. Most buildings in this market were built in 1986 and are Class B.