On average, listings lease in the $20's per square foot per year. The Des Moines submarket is experiencing a a rise in rates. In the last 3 months, the median rate went up $4 per sqft per year. That's a 18% rise in rent.
In the last 90 days, 33 listings have come on the market, which means new availabilities most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. About 3% of the office spaces in the Des Moines are subleases, so you will probably have to focus your search on direct office leases. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
Even though the median size is 3,000 sqft, there are still 0 new availabilities below 2,000 sqft. Most properties in this area are around 2 floors. Most buildings in this market were built in 1979 and are Class B.