It's a common assumption in microecnomics that competition always drives down prices. It doesn't always - every other business knows that starting a price war is suicide, as everyone will lose. The competitors will try to steal business with a similar price, and try to compete on branding and service.

Actually, his best bet is to get a retail space, then get a friend to make a few calls to the cops about suspicious vans around the Chinese embassy, and ask if they are allowed to be there. The legal system is geared against "unofficial" (i.e. poor) business people - itinerant vendors and bugger all rights.