Gepperth's will generally have it, along with rendered duck and goose fact. It will be frozen, if that's of concern. They also make some great stocks. In addition to the regulars, they'll occasionally offer duck, rabbit, venison stocks.
Any of the pre-packaged stuff--especially in Latin groceries--is going to be no better than Armour. If you don't have luck in the Polish stores--try an Italian butcher. Here in NYC, there are a few shops that make their own lard and it's very good.