On average, listings lease in the $30's per square foot per year. The Sumter County submarket is going through a a rise in rates. In the last 3 months, the median rate rose $17 per sqft per year. That's a 108% rise in rent.
In the last 90 days, 5 listings have been posted online, which means listings 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,000 sqft. Most buildings in this market were built in 2006 and are Class A.