On average, listings lease in the $20's per square foot per year. The Des Moines region is experiencing a a boost in rates. In the last 3 months, the median rate increased $4 per sqft per year. That's a 18% increase in rent.
In the last 90 days, 28 listings have been made available, which means new listings are probably going fast. You'll want to be prepared to make an offer immediately. About 4% of the available space in the Des Moines 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 posted, so finding a space for a small business might be tough.
Even though the median size is 2,540 sqft, there are still 0 leases below 2,000 sqft. Most properties in this market are close to 2 stories. Most buildings in this area were built in 1977 and are Class B.