Most listings are in the $20's per square foot per year. The Westmont submarket is seeing a a boost in rates. In the last 3 months, the median rate increased $3 per sqft per year. That's a 19% increase in rent.
Compared to the rest of the Chicagoland market, the Westmont region has lower rates, so you should have no trouble finding a great deal in this undervalued submarket.
In the last 90 days, 19 listings have been made available, which means new availabilities most likley are leasing quickly. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,780 sqft. Most buildings in this area are around 1 floors. Most buildings in this area were built in 1988 and are Class A.