Most listings are in the $10's per square foot per year. The Yellowstone County region is going through a a rise in rates. In the last 3 months, the median rate rose $3 per sqft per year. That's a 15% increase in rent.
In the last 90 days, 57 listings have come on the market, so you'll want to check back regularly for new listings. About 130% of the available leases in the Yellowstone County are subleases, so you might be able to find a shorter term or below market rent. 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 2,340 sqft. Most buildings in this region are approximately 2 floors. Most buildings in this market were built in 1979 and are Class A.