On average, listings lease in the $20's per square foot per year. The Evergreen Park submarket is going through a an increase in rates. In the last 3 months, the median rate rose $21 per sqft per year. That's a Inf% increase in rent.
Compared to the rest of the Chicagoland market, the Evergreen Park submarket has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 14 listings have been listed, 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 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 1,040 sqft. Most properties in this area are approximately 2 floors. Most buildings in this market were built in 1965 and are Class C.