Most listings are in the $10's per square foot per year. The Missoula County submarket is going through a decrease in rates. In the last 3 months, the median rate decreased $1 per sqft per year. That's a 4% decrease in rent.
In the last 90 days, 8 listings have been posted online, which means new listings 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,750 sqft. Most buildings in this market are close to 1 floors. Most buildings in this area were built in 1981 and are Class A.