Actually that is not true. There are all kinds of legal items that can be bought or sold illegally. Cigarettes are a prime example of a legal susbstance that is a huge money maker in the black market. One truckload of the things can net the smuggler 2million dollars.

That may very well be true, but the reason is the high level of taxation, not the cost of production and marketing.

I'm not allowed to run the train
the whistle i can't blow
I'm not allowed to say how fast the railroad train can go
Im not allowed to shoot off steam or even ring the bell
But let the damn train jump the track and see who catches hell