The typical asking rate per listing is in the $20's per square foot per year. The Missoula region is seeing a an increase in rates. In the last 3 months, the median rate rose $2 per sqft per year. That's a 10% increase in rent.
In the last 90 days, 40 listings have been listed, which means new availabilities most likley are going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,560 sqft. Most properties in this region are close to 2 stories. Most buildings in this region were built in 1981 and are Class A.