Most listings are in the $10's per square foot per year. The Smithfield submarket is going through a a boost in rates. In the last 3 months, the median rate went up $18 per sqft per year.
Compared to the rest of the The Triangle market, the Smithfield submarket has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 9 listings have been listed, which means office spaces are probably going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 190 sqft. Most properties in this region are close to 1 stories. Most buildings in this region were built in 1995 and are Class B.