Look for Korean markets. They have really nice thinly sliced ribeyes.
They sell them for grill top cooking but I use them for delicious Philadelphia Cheesesteak Sandwiches...
That was going to be my suggestion too---great minds think alike!
There is a Korean chain across the country called H-Mart, maybe they have a location near you. There is a Japanese chain called Mitsuwa Marketplace, also a national chain. Also one called Marukai. The ribeye is sliced for shabu shabu, sukiyaki or Korean barbecue. It is what I get when I do cheesesteaks and it is perfect.