I think I share Tony's dislike of the idea of the equivalent of Big Tobacco forming but around hard drugs. Nobody wants Joe Camel brand cocaine.
Are you familiar with the Washington and Colorado markets? Most of the stores function as more similar to farmer's markets or consignment shops. They get their product from small growers, and there is no megacorporations involved or marketing.
I think this dynamic will change rapidly once recreational commercial markets in California and Canada appear sometime in 2017-18, and transporting marijuana across state and even national lines becomes legal.