On average, listings lease in the $30's per square foot per year. The Spearfish region is going through a an increase in rates. In the last 3 months, the median rate rose $32 per sqft per year.
In the last 90 days, 15 listings have been posted online, which means spaces might be 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 500 sqft. Most buildings in this area are close to 1 floors. Most buildings in this region were built in 1995.