Most listings are in the $10's per square foot per year. The Tulsa submarket is going through a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 4% rise in rent.
In the last 90 days, 180 listings have been listed, so you'll want to check back regularly for new listings. About 5% of the available leases in the Tulsa are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 2,000 sqft. Most properties in this area are close to 2 floors. Most buildings in this market were built in 1981 and are Class B.