try oriental groceries... specifically Chinese. In large metro areas there are usually several. If you cannot read Oriental labels, take someone that can read them with you if you want to purchase anything else... some items do not have English translations written on the labels.
you can also make a bone broth (make sure the bones have the marrow and joint cartilage intact), cooking it down into a gelatin. The above recipe is the same for a simple bone broth\stock\gelatin... there is usually more than one way to get to the same end.