Compared to the rest of the Fairfield market, the Cos Cob region has more expensive rates, and you'll need to pay a premium to be in this hot submarket.
In the last 90 days, 4 listings have come on the market, which means new availabilities most likley are going fast. You'll want to be prepared to make an offer immediately. 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 510 sqft. Most properties in this area are around 3 stories. Most buildings in this area were built in 1967 and are Class A.