The typical asking rate per listing is in the $10's per square foot per year. The Berwyn submarket is going through a an increase in rates. In the last 3 months, the median rate rose $18 per sqft per year.
Compared to the rest of the Chicagoland market, the Berwyn submarket has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 3 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. 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 6,000 sqft, there are still 0 office spaces below 2,000 sqft. Most buildings in this market are close to 1 stories. Most buildings in this market were built in 1911 and are Class C.