On average, listings lease in the $10's per square foot per year. The South Philadelphia submarket is going through a a rise in rates. In the last 3 months, the median rate rose $20 per sqft per year.
Compared to the rest of the Philadelphia market, the South Philadelphia region has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 7 listings have come on the market, which means new listings 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.
Even though the median size is 6,490 sqft, there are still 0 new listings below 2,000 sqft. Most buildings in this area are around 4 floors. Most buildings in this area were built in 1930 and are Class B.