Me on my soap box - support the little guy, buy local!What you need to do if you can is make friends with the folks that own or run a small local meat shop. Even better, buy half a pig from a local farmer. I live in a fairly low population but still urban area, but I have a choice of people I could be buying locally produced critters and varmints from not that far away. My local shop can get me whatever I need with a few days notice - the owner supplies his own beef, their pork supplier is an operation about a 45min drive from here.
The chain stores don't really cut meat like they used to in the old days (I'm not that old, 41). I can still remember seeing actual sides of beef hanging in the back coolers at the local grocery stores. They don't get their meat that way anymore, it comes in chunks in big vac bags. Chances are your local chain grocery store can't get you the fat you need because it never came to them in the first place.