Why would they pay more? First, convenience - it's right in the store, you can just buy it without having to do a shady deal where you might get killed. Second,

Why would they pay more? First, convenience - it's right in the store, you can just buy it without having to do a shady deal where you might get killed. Second, big drug companies at scale will be able to manufacture for much less. Third, there is a premium you have to pay for anything illegal to compensate the seller for the risk. So they are paying higher than it's worth anyways.