The typical asking rate per listing is in the $20's per square foot per year. The Willowbrook submarket is seeing a an increase in rates. In the last 3 months, the median rate increased $20 per sqft per year.
Compared to the rest of the Chicagoland market, the Willowbrook region has smaller rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 2 listings have come on the market, which means office spaces 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 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 2,110 sqft. Most buildings in this market are close to 1 floors. Most buildings in this market were built in 1979 and are Class B.