The typical asking rate per listing is in the $20's per square foot per year. The Ada County submarket is going through a a boost in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 7% rise in rent.
In the last 90 days, 342 listings have come on the market, so you'll want to check back regularly for new listings. About 3% of the available leases in the Ada County are subleases, so you will probably have to consider a longer term lease. 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 2,220 sqft. Most buildings in this area are approximately 1 floors. Most buildings in this area were built in 1998 and are Class A.