Most listings are in the $10's per square foot per year. The South Philadelphia submarket is going through a an increase in rates. In the last 3 months, the median rate increased $20 per sqft per year.
Compared to the rest of the Philadelphia market, the South Philadelphia region has smaller rates, so you should have no trouble finding a great deal in this depreciated region.
In the last 90 days, 7 listings have been made available, which means new listings most likley are going fast. You'll want to be prepared to make an offer immediately. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
Even though the median size is 6,490 sqft, there are still 0 listings below 2,000 sqft. Most properties in this region are close to 4 stories. Most buildings in this region were built in 1930 and are Class B.