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 increased $10 per sqft per year. That's a 47% rise in rent.
In the last 90 days, 18 listings have been listed, which means new listings most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. About 6% of the listings in the Dayton are subleases, so you will probably have to consider a longer term lease. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 2,260 sqft. Most buildings in this area are around 3 floors. Most buildings in this area were built in 1971 and are Class B.