On average, listings lease in the $20's per square foot per year. The Northwest Philadelphia region is going through a a rise in rates. In the last 3 months, the median rate rose $4 per sqft per year. That's a 16% increase in rent.
Compared to the rest of the Philadelphia market, the Northwest Philadelphia region has less expensive rates, so you should have no trouble finding a great deal in this discounted region.
In the last 90 days, 14 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 740 sqft. Most buildings in this region are close to 3 stories. Most buildings in this market were built in 1905 and are Class C.