Most listings are in the $20's per square foot per year. The Northbrook submarket is going through a a boost in rates. In the last 3 months, the median rate went up $5 per sqft per year. That's a 28% increase in rent.
In the last 90 days, 4 listings have been made available, which means spaces are probably going fast. You'll want to be prepared to tour spaces as quick as possible. About 75% of the available space in the Northbrook 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 available, so finding a space for a small business might be tough.
Even though the median size is 2,920 sqft, there are still 0 leases below 2,000 sqft. Most properties in this area are approximately 2 floors. Most buildings in this area were built in 1977.