On average, listings lease in the $20's per square foot per year. The Springfield submarket is going through a a rise in rates. In the last 3 months, the median rate went up $1 per sqft per year. That's a 7% rise in rent.
In the last 90 days, 38 listings have been listed, which means new availabilities most likley are leasing quickly. You'll want to be prepared to make an offer immediately. 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 2,170 sqft. Most buildings in this area are approximately 2 stories. Most buildings in this market were built in 1908 and are Class A.