Plants are hit or miss. Captain Nemo's has a decent selection and every now and then will have some hard to find plants.
Believe it or not, Petco's have some good crypts and anubias at good prices in stock. Upper Darby, Ardmore, and KOP suprised me. Nothing fancy...nothing rare...but for crypts and anubias...not bad.
Premium Aquatics in Newark DE will also have some plants...hit or miss...but the people are friendly and can order most stuff for you.
Lastly, Aquarium Center in Jersey is worth a shot. Not too far out of philly across the bridge. I reallly like this store.