On average, listings lease in the $10's per square foot per year. The Des Moines region is seeing a decline in rates. In the last 3 months, the median rate decreased $3 per sqft per year. That's a 17% decrease in rent.
Compared to the rest of the Seattle Metropolitan Area market, the Des Moines region has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 2 listings have come on the market, which means listings most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. 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 1,670 sqft. Most properties in this area are around 2 stories. Most buildings in this market were built in 1984 and are Class B.