Most listings are in the $20's per square foot per year. The Darien region is experiencing a an increase in rates. In the last 3 months, the median rate went up $4 per sqft per year. That's a 22% increase in rent.
Compared to the rest of the Chicagoland market, the Darien submarket has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 5 listings have come on the market, which means listings most likley are going fast. You'll want to be prepared to make an offer immediately. 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 3,000 sqft, there are still 0 new listings below 2,000 sqft. Most buildings in this area are around 1 stories. Most buildings in this market were built in 1990 and are Class B.