Most listings are in the $10's per square foot per year. The Rock Island submarket is going through a a boost in rates. In the last 3 months, the median rate increased $1 per sqft per year. That's a 4% increase in rent.
In the last 90 days, 25 listings have been made available, which means leases might be going fast. You'll want to be prepared to tour spaces as quick as possible. About 4% of the available space in the Rock Island are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 2,500 sqft. Most properties in this region are close to 2 stories. Most buildings in this market were built in 1971 and are Class B.