Most listings are in the $10's per square foot per year. The South Dakota 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 5% increase in rent.
In the last 90 days, 125 listings have been posted online, so you'll want to check back regularly for new listings. About 2% of the office spaces in the South Dakota are subleases, so you will probably need to consider the implications of signing a direct lease with the building. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,040 sqft. Most properties in this area are around 2 floors. Most buildings in this region were built in 1990 and are Class A.