Most listings are in the $10's per square foot per year. The Clarksburg region is going through a a rise in rates. In the last 3 months, the median rate rose $15 per sqft per year.
In the last 90 days, 0 listings have been listed, which means leases most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About Inf% of the listings in the Clarksburg 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 available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 240 sqft. Most buildings in this region were built in 1998 and are Class B.