Most listings are in the $20's per square foot per year. The Ada County submarket is going through a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 7% increase in rent.
In the last 90 days, 290 listings have been posted online, so you'll want to check back regularly for new listings. About 2% of the office spaces in the Ada County are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 2,290 sqft. Most buildings in this market are close to 1 floors. Most buildings in this area were built in 1999 and are Class A.