The typical asking rate per listing is in the $30's per square foot per year. The Charleston County submarket is going through a an increase in rates. In the last 3 months, the median rate increased $3 per sqft per year. That's a 11% increase in rent.
In the last 90 days, 240 listings have been listed, so you'll want to check back regularly for new listings. About 4% of the available leases in the Charleston County are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 2,400 sqft. Most properties in this region are approximately 2 floors. Most buildings in this region were built in 1989 and are Class A.