I don't know that I've ever thought to look for pork rub at the grocery store. I'm sure they have some, though. I usually make my own, or go with something from online or BBQ store sources. As others have mentioned, Ace Hardware usually has a great selection of various rubs and sauces. Oakridge Secret Weapon is awesome. Recently, I tried Hardcore Carnivore's Red on a pork butt - it was really good, and less sweet than a lot of pork rubs.