I've got a couple small jars in my basement, but I'm not at all sure about shipping it.

Get ahold of a book called "Foxfire 5." There are quite detailed instructions in it for making saltpeter and, beyond that, your very own gunpowder.

The ingredients of the KNO3 include old manure (chicken is best) and what is euphemistically called "chamber lye."

I would say, "Have a blast!" but I'd better not.