Not sure where in the states you are located, but international supermarkets are likely to carry it, both pre-made (and without additives) or the necessary ingredients. Asian markets...as well as Latin, etc...
Asian markets where I live (as many if not more than Anerican) sell bones specifically for it.
I’ve seen the packaged bone broth at Vons which is Safeway.
“Not sure where in the states you are located, but international supermarkets are likely to carry it, both pre-made (and without additives) or the necessary ingredients. Asian markets...as well as Latin, etc...”
I know it is widely available.
People just don’t eat it like they used to eat it. There is a strong preference toward muscle meat in modern diets, which is leaving out key amino acids.
You can go buy a several pound bag (or jug) of kosher beef gelatin powder for less than a couple of dollars at any store with a kosher section (which most have).