Most listings are in the $10's per square foot per year. The North Haven region is going through a a rise in rates. In the last 3 months, the median rate rose $18 per sqft per year.
In the last 90 days, 7 listings have been made available, which means spaces most likley are going fast. You'll want to be prepared to make an offer immediately. About 129% of the office spaces in the North Haven are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 2,110 sqft. Most buildings in this region are around 2 stories. Most buildings in this region were built in 1975 and are Class B.