The typical asking rate per listing is in the $10's per square foot per year. The Harrisburg submarket is going through a decrease in rates. In the last 3 months, the median rate fell $0 per sqft per year. That's a 2% decrease in rent.
In the last 90 days, 22 listings have been listed, which means listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 5% of the listings in the Harrisburg are subleases, so you will probably need to sign a longer term lease with the landlord directly. 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 1,730 sqft. Most properties in this area are close to 3 floors. Most buildings in this region were built in 1935 and are Class B.