The typical asking rate per listing is in the $30's per square foot per year. The Mount Pleasant submarket is going through a decline in rates. In the last 3 months, the median rate decreased $2 per sqft per year. That's a 6% decline in rent.
In the last 90 days, 20 listings have been made available, which means spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 10% of the listings in the Mount Pleasant are subleases, so you will probably have to focus your search on direct office leases. 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 2,260 sqft. Most buildings in this market are around 2 floors. Most buildings in this market were built in 2002 and are Class A.