Welcome to FT. Try sidestep.com. It is a search engine that will look on all of the airline websites and major travel sites to find the best price. I'm guessing PHL or BWI will probably be a little cheaper than PIT, due to the increased competition at those airports. EWR has also been cheap for me, if that isn't too far for you.

You might want to post a similar question on either the Travelbuzz or Mileage Run Forums, or better yet, have a Mod move this. The MR folks are the absolute experts at finding good fares.