Most listings are in the $10's per square foot per year. The Duncan region is going through a an increase in rates. In the last 3 months, the median rate went up $15 per sqft per year.
In the last 90 days, 4 listings have come on the market, which means office spaces might be going fast. You'll want to be prepared to tour spaces as quick as possible. 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 1,100 sqft. Most buildings in this market are approximately 2 floors.