Black marketeers are subject to the same economic laws that everyone else is.It also allows for better Control over the price. Criminals can basically charge whatever they want for marijuana. A lot of cities marijuana markets are controlled by one or two major gangs. And the dealers connected with those gangs can charge whatever they want.
Taking those gangs control of the product away from the free market to take over, And prices will go back down to where they are based on market factors instead of what criminals want to charge.
I can go to california and buy an ounce of weed for far less than I would be able to buy it in a state where it's still illegal. Even with the added sales taxes.
They have next to no overhead and don't have to fork over the protection racket cut to the gubmint.....Street dealers are cheaper, and have high quality product as well.....The only thing they won't have is $100,000 of inventory on hand.