The typical asking rate per listing is in the $10's per square foot per year. The Ballwin submarket is experiencing a a boost in rates. In the last 3 months, the median rate went up $17 per sqft per year. That's a Inf% rise in rent.
In the last 90 days, 9 listings have been listed, 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 1,210 sqft. Most buildings in this region are approximately 2 stories. Most buildings in this area were built in 1990 and are Class C.