On average, listings lease in the $20's per square foot per year. The Riverside submarket is going through a an increase in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 4% increase in rent.
Compared to the rest of the Chicagoland market, the Riverside region has more expensive rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 1 listings have been posted online, which means spaces might be leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 100% of the listings in the Riverside are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 2,340 sqft. Most buildings in this market were built in 1871 and are Class B.