Most listings are in the $20's per square foot per year. The Willow Street region is going through a a rise in rates. In the last 3 months, the median rate increased $24 per sqft per year.
In the last 90 days, 2 listings have come on the market, which means office spaces are probably leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,080 sqft. Most buildings in this market were built in 2005 and are Class B.