On average, listings lease in the $20's per square foot per year. The Charleston region is seeing a a rise in rates. In the last 3 months, the median rate went up $26 per sqft per year.
In the last 90 days, 8 listings have been made available, which means leases are probably going fast. You'll want to be prepared to tour spaces as quick as possible. About 25% of the office spaces in the Charleston are subleases, so you might be able to find a shorter term or below market rent. 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 810 sqft. Most buildings in this region are approximately 5 stories. Most buildings in this market were built in 1984 and are Class B.