On average, listings lease in the $10's per square foot per year. The Mount Pleasant region is experiencing a a rise in rates. In the last 3 months, the median rate rose $18 per sqft per year.
In the last 90 days, 4 listings have come on the market, which means new availabilities are probably going fast. You'll want to be prepared to make an offer immediately. About 300% of the available space in the Mount Pleasant 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 posted, 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 market are around 1 stories. Most buildings in this region were built in 1979 and are Class C.