Most listings are in the $30's per square foot per year. The Westchester submarket is going through a a rise in rates. In the last 3 months, the median rate increased $15 per sqft per year. That's a 76% rise in rent.
Compared to the rest of the Chicagoland market, the Westchester region has more expensive rates, and you'll have to negotiate above asking rent to be in this hot region.
In the last 90 days, 55 listings have been posted online, so you'll want to check back regularly for new listings. About 15% of the available leases in the Westchester 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 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 2,390 sqft. Most buildings in this area are approximately 2 stories. Most buildings in this region were built in 1986 and are Class A.