The link above is to add some humor to the circumstances of which is far to serious an issue to dismiss to a video game. But, like the understanding in this video game, "The price of the various items is controlled by market conditions."
The 'real' world of 'underworld' weapons trade is established on supply and demand. It doesn't matter the 'item' so much as the government regulation of it and the discovery by consumers they really don't have to do without so much as just 'pay the price' for illegitimate trade. The Gun Lobby never takes a stand against this undermining aspect of Gun Regulation NOR does it bother to 'lobby' any government to stop the illegal trade. Why? Because those guns are manufactered by someone and it ain't in Uncle George's backyard, okay?