The typical asking rate per listing is in the $10's per square foot per year. The Warrenville region is going through a decline in rates. In the last 3 months, the median rate fell $11 per sqft per year. That's a 41% decline in rent.
Compared to the rest of the Chicagoland market, the Warrenville submarket has less expensive rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 19 listings have been made available, which means new availabilities 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,430 sqft. Most buildings in this market are around 2 stories. Most buildings in this area were built in 1999 and are Class B.