The typical asking rate per listing is in the $20's per square foot per year. The Missouri region is seeing a an increase in rates. In the last 3 months, the median rate rose $2 per sqft per year. That's a 8% increase in rent.
In the last 90 days, 843 listings have come on the market, so you'll want to check back regularly for new listings. About 2% of the listings in the Missouri are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 2,500 sqft. Most properties in this region are approximately 2 floors. Most buildings in this market were built in 1984 and are Class B.