On average, listings lease in the $20's per square foot per year. The West Chester submarket is seeing a decline in rates. In the last 3 months, the median rate fell $3 per sqft per year. That's a 10% decline in rent.
In the last 90 days, 7 listings have been made available, which means spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 214% of the available space in the West Chester 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 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 1,000 sqft. Most buildings in this area are around 3 floors. Most buildings in this region were built in 1930 and are Class A.