Most listings are in the $20's per square foot per year. The Williston region is going through a decrease in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 5% decrease in rent.
In the last 90 days, 9 listings have been posted online, which means listings are probably 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 560 sqft. Most buildings in this area were built in 2011 and are Class A.