This is pretty daft. If the supply contracts, then you already have fewer guns available. An increase in price means, all other things being equal, fewer guns will be purchased. Regulations really do work.
Guns are not like drugs. People become addicted to drugs. A driver for guns is that one's enemies possess guns, which sets off an arms race: People need guns because of a threat posed by guns.
As far as organized crime goes, I'd guess drugs are substantially more lucrative in well-ordered societies. Guns are necessary to facilitate criminal activity. Also, guns are not as easily smuggled as drugs: As mumblethrax observed, "I've never seen anyone swallow a condom full of guns." They have drugs in Australia and Japan, but not as many guns. In Australia, criminals have reportedly resorted to a lending program for firearms. Drugs are not as bulky, and worth more by weight. If guns become worth more than uncut heroin or cocaine, you're not going to have as many buyers -- which is related to another point: the vast majority of customers are not purchasing drugs by the kilo. Drugs are divisible in ways that firearms are not, which, all other things being equal, makes them easier to move.