The typical asking rate per listing is in the $20's per square foot per year. The Williston submarket is going through a decline in rates. In the last 3 months, the median rate decreased $1 per sqft per year. That's a 5% decrease in rent.
In the last 90 days, 9 listings have come on the market, which means leases most likley are leasing quickly. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet on the market, 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 region were built in 2011 and are Class A.