Most listings are in the $30's per square foot per year. The Mount Pleasant submarket is experiencing a a rise in rates. In the last 3 months, the median rate went up $3 per sqft per year. That's a 9% increase in rent.
In the last 90 days, 40 listings have been posted online, which means new listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 10% 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 2,450 sqft. Most properties in this area are close to 2 stories. Most buildings in this market were built in 2002 and are Class A.