On average, listings lease in the $30's per square foot per year. The Forest Hills submarket is going through a an increase in rates. In the last 3 months, the median rate rose $36 per sqft per year.
In the last 90 days, 2 listings have come on the market, which means listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 100% of the office spaces in the Forest Hills are subleases, so you might be able to snag a great spot on a short term. 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 200 sqft. Most buildings in this market are around 2 stories. Most buildings in this area were built in 1940 and are Class B.