Compared to the rest of the Chicagoland market, the Riverside submarket has lower rates, so you should have no trouble finding a great deal in this discounted submarket.
In the last 90 days, 1 listings have been made available, which means spaces are probably going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,550 sqft. Most buildings in this market were built in 1871 and are Class B.