That unit is not your average daily user product and the charger is not just a 510 thread USB.
The business is NOT saturated by any means and is growing leaps and bounds.
The regulations that are most likely to come down are for selling nicotine Online. If you have a brick and mortar store, I don't see any problems in the immediate future.
Brian837 - You say that 7-11 sells shit, not entirely true. We have our line of e-juice in 400+ retail locations that include 7-11, Cigarette Shops, and AM-PM
To the OP - The business is really price driven. You want to make sure you have a good amount of inventory with a niche. For instance, you could have a Mod that you are an exclusive dealer for or a line of e-juice that is exclusive to your store.
E-juice is a key component that I feel not enough attention is given to at most of these retail locations. When a customer walks in and wants a 12mg nicotine blueberry flavor juice and you don't have it, that customer is lost. make sure you have a good supply of juices.
Obviously, like any other business, there is a lot more to the whole picture, but believe me when I say there is still money to be made.
