On average, listings lease in the $20's per square foot per year. The St. Peters submarket is experiencing a a rise in rates. In the last 3 months, the median rate increased $5 per sqft per year. That's a 22% increase in rent.
In the last 90 days, 21 listings have been listed, which means listings might be leasing quickly. You'll want to be prepared to make an offer immediately. About 5% of the listings in the St. Peters 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 950 sqft. Most properties in this market are close to 1 stories. Most buildings in this area were built in 1999 and are Class B.