Most listings are in the $30's per square foot per year. The Dayton region is going through a an increase in rates. In the last 3 months, the median rate went up $17 per sqft per year. That's a 114% rise in rent.
In the last 90 days, 22 listings have come on the market, which means spaces most likley are going fast. You'll want to be prepared to make an offer immediately. About 18% of the available leases in the Dayton are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 3,300 sqft, there are still 0 office spaces below 2,000 sqft. Most buildings in this area are approximately 2 floors. Most buildings in this region were built in 1972 and are Class B.