The typical asking rate per listing is in the $10's per square foot per year. The Rock Island submarket is going through a a rise in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 4% rise in rent.
In the last 90 days, 25 listings have been posted online, which means new availabilities are probably going fast. You'll want to be prepared to make an offer immediately. About 4% of the office spaces in the Rock Island are subleases, so you will probably have to consider a longer term lease. 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 2,500 sqft. Most properties in this area are close to 2 floors. Most buildings in this region were built in 1971 and are Class B.