Most listings are in the $20's per square foot per year. The St. Louis County region is going through a decrease in rates. In the last 3 months, the median rate fell $3 per sqft per year. That's a 11% decrease in rent.
In the last 90 days, 411 listings have been made available, so you'll want to check back regularly for new listings. About 76% of the listings in the St. Louis County are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 2,430 sqft. Most buildings in this area are around 2 stories. Most buildings in this region were built in 1982 and are Class B.