Most listings are in the $10's per square foot per year. The Florissant submarket is going through a a boost in rates. In the last 3 months, the median rate increased $1 per sqft per year. That's a 7% increase in rent.
In the last 90 days, 20 listings have come on the market, which means spaces are probably going fast. You'll want to be prepared to make an offer immediately. 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 320 sqft. Most properties in this market are around 1 floors. Most buildings in this market were built in 1975 and are Class C.