Most listings are in the $20's per square foot per year. The St. Louis County region is seeing a a rise in rates. In the last 3 months, the median rate went up $28 per sqft per year.
In the last 90 days, 411 listings have been posted online, so you'll want to check back regularly for new listings. About 65% of the available leases in the St. Louis County are subleases, so you might be able to snag a great spot on a short term. There aren't many listings below 2,000 square feet posted, 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 market are approximately 2 floors. Most buildings in this area were built in 1982 and are Class B.