There are roughly 400K to 500K machine-guns in the possession of private citizens in the US. Prices are based on what the market will bear. No set pricing. The best place to start the purchase of a MG is at a class III FFL dealer. That dealer usually has customers calling him stating that their Machine-gun(s) is for sale, dealer has a gun on consignment or the dealer may even have a gun or two of his own for sale. It is a very small community and places like Subguns.com is the place where they gather. Other than at a gun show or word of mouth, there is no other place to find these types of firearms for sale.