You’re talking about a gray market, like in legal cannabis states where prices are still high and there are ridiculous barriers preventing those who were growing cannabis illegaly before “legalization”(or rather prohibition 2.0) from entering the industry so they sell at a lower price and undercut the market. But these people are not multi million dollar cartels and in 97 cases out of 100 cartels have already moved out of the cannabis trade or they have taken steps to enter the legal trade. Im talking about a commercial environment where violence is not needed to protect the producer and their profits, the main idea behind prohibition is this enforcing of abstinence only moral Puritanism built on religious fundamentalism and racism/ white supremacy. There is definitely a way to undercut the entire black market but it is almost impossible within a capitalistic economy the leas regulated the more unfeasible it is.