On average, listings lease in the $10's per square foot per year. The St. Charles region is experiencing a decrease in rates. In the last 3 months, the median rate decreased $0 per sqft per year. That's a 2% decrease in rent.
In the last 90 days, 20 listings have been made available, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,800 sqft. Most properties in this region are around 2 stories. Most buildings in this area were built in 1993 and are Class B.