The typical asking rate per listing is in the $40's per square foot per year. The Thornwood submarket is going through a a boost in rates. In the last 3 months, the median rate rose $43 per sqft per year.
In the last 90 days, 5 listings have been posted online, which means listings might be leasing quickly. You'll want to be prepared to make an offer immediately. About 100% of the office spaces in the Thornwood are subleases, so you might be able to find a shorter term or below market rent. 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 700 sqft. Most buildings in this area were built in 1998.