Compared to the rest of the Philadelphia market, the Northwest Philadelphia submarket has lower rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 14 listings have been listed, which means office spaces most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 36% of the available space in the Northwest Philadelphia are subleases, so you might be able to snag a great spot on a short term. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 420 sqft. Most properties in this area are around 3 floors. Most buildings in this area were built in 1905 and are Class C.