Most listings are in the $10's per square foot per year. The St. Peters submarket is experiencing a decline in rates. In the last 3 months, the median rate decreased $8 per sqft per year. That's a 29% decline in rent.
In the last 90 days, 28 listings have been listed, which means spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 29% of the available leases in the St. Peters 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,310 sqft. Most properties in this area are close to 1 floors. Most buildings in this region were built in 1999 and are Class B.