On average, listings lease in the $70's per square foot per year. The Mount Pleasant region is experiencing a an increase in rates. In the last 3 months, the median rate rose $37 per sqft per year. That's a 109% increase in rent.
In the last 90 days, 35 listings have been posted online, which means spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 3% of the available space in the Mount Pleasant 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 210 sqft. Most buildings in this market are close to 2 stories. Most buildings in this region were built in 2002 and are Class A.