Most listings are in the $0's per square foot per year. The Wentzville submarket is experiencing a decline in rates. In the last 3 months, the median rate decreased $18 per sqft per year. That's a 100% decline in rent.
In the last 90 days, 5 listings have come on the market, which means leases most likley are 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 sqft. Most properties in this market are around 2 floors. Most buildings in this area were built in 1986 and are Class B.