I was gonna mention pats or geno's to if you want a true philly cheese steak. Be prepared on how to say it, or you will get looked at kinda awkward.
Pats:
http://www.patskingofsteaks.com/
Geno's:
http://www.genosteaks.com/
How to order one:
http://www.bestcheesesteaks.com/ordering.htm Like I said, make sure you read this very carefully, or you will regret it.