Most listings are in the $10's per square foot per year. The Harrisburg submarket is going through a decline 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, 21 listings have come on the market, which means office spaces most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 5% of the available leases in the Harrisburg are subleases, so you will probably have to focus your search on direct office leases. 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 1,600 sqft. Most properties in this market are around 3 stories. Most buildings in this region were built in 1935 and are Class B.