Most listings are in the $10's per square foot per year. The Iowa submarket is going through a a rise in rates. In the last 3 months, the median rate went up $19 per sqft per year.
In the last 90 days, 1192 listings have been made available, so you'll want to check back regularly for new listings. About 40% of the available leases in the Iowa are subleases, so you might be able to find a shorter term or below market rent. 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 2,250 sqft. Most buildings in this region are close to 1 stories. Most buildings in this market were built in 1985 and are Class A.