Most listings are in the $20's per square foot per year. The Ballwin region is seeing a a rise in rates. In the last 3 months, the median rate went up $5 per sqft per year. That's a 27% increase in rent.
In the last 90 days, 12 listings have come on the market, which means spaces are probably leasing quickly. 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 1,140 sqft. Most buildings in this region are close to 3 floors. Most buildings in this area were built in 1972 and are Class B.