The typical asking rate per listing is in the $30's per square foot per year. The West Chester submarket is going through a a boost in rates. In the last 3 months, the median rate increased $1 per sqft per year. That's a 5% increase in rent.
In the last 90 days, 8 listings have been made available, which means spaces most likley are going fast. You'll want to be prepared to tour spaces as quick as possible. 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 630 sqft. Most buildings in this market are close to 3 floors. Most buildings in this market were built in 1930 and are Class C.