Most listings are in the $10's per square foot per year. The Yellowstone County region is going through a decline in rates. In the last 3 months, the median rate fell $2 per sqft per year. That's a 8% decline in rent.
In the last 90 days, 57 listings have been made available, so you'll want to check back regularly for new listings. 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 920 sqft. Most buildings in this region are approximately 2 stories. Most buildings in this area were built in 1983 and are Class A.