I have been to all 5 local grocery stores in town (not WalMart yet) talking to the guys in the meat dept. They all say they never have any beef bones...no soup bones, no marrow bones, no dog bones, not even cross cut beef shanks. The only thing available seems to be pork: feet, neck, ribs, etc. Of course this is all conventional pork. Is it even worth it to make stock out of these pork bones? I have a calf reserved to buy next fall from a local farmer (it won't be totally pastured, but much better than feedlot). So do I bother with pork broth or not? Also, I can get pork fat from a source to render my own lard, but again this will not be pastured pork. Do I go down this road or not?
I would say don't bother, aside from the PUFAs in conventionally raised pork, pork broth is not the most versatile broth. Its good for some things for sure, like asian style soups and braising greens, but beef stock or chicken stock is much more versatile. So all in all, I just wouldn't bother. Look online for beef bones or try eatwild.com and see if there is anything near where you are. You could also ask the farmer you will be dealing with if he has any buddies that do pork or lamb.
I use conventional pork bones for stock because they're so cheap and plentiful. If it's the only way to get real bone broth, I say go for it. Ditch the fat that settles on top and enjoy the broth.
It's far better than no broth at all.
There are ways to mail order grassfed/pastured animal products...have you looked into that at all? I personally would continue to strive to find the much more highly nutritious and humanely raised animals' bones and fat. http://www.eatwild.com/ http://www.grasslandbeef.com/StoreFront.bok
Most stores get their meat pre-cut (at least most of the way cut) that is why you can't get bones. Get out that old fashioned and obsolete thing called a phone book and see if you can find a butcher shop, you are more likely to get bones there.