Most listings are in the $20's per square foot per year. The Glen Ellyn submarket is going through a a boost in rates. In the last 3 months, the median rate increased $22 per sqft per year.
Compared to the rest of the Chicagoland market, the Glen Ellyn region has lower rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 6 listings have been made available, which means new listings 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 on the market, so finding a space for a small business might be tough.
Even though the median size is 4,090 sqft, there are still 0 office spaces below 2,000 sqft. Most buildings in this market are close to 1 stories. Most buildings in this market were built in 1983 and are Class A.