Most listings are in the $10's per square foot per year. The Duncan region is going through a a boost in rates. In the last 3 months, the median rate increased $18 per sqft per year.
In the last 90 days, 1 listings have been made available, which means office spaces are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 1,700% of the listings in the Duncan are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 250 sqft. Most properties in this region are around 2 stories. Most buildings in this region were built in 1978 and are Class C.