On average, listings lease in the $20's per square foot per year. The Butler County submarket is going through a a boost in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 3% increase in rent.
In the last 90 days, 14 listings have been made available, which means listings 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 410 sqft. Most properties in this area are approximately 1 floors. Most buildings in this area were built in 2002 and are Class B.