He is certainly taking the right approach in combining selling homebrewing supplies with something that actually produces income. How many people are in the area? Any clue about the number of homebrewers?
At first, he will probably want to purchased prepackaged supplies from places like freshops, briess, white labs, etc. I'd say no kits, but canned unhopped extract and dried extracts would be a good idea. Stay away from liquid yeasts or only stock a few of the more standard ones. Three or four brewing books. Bottles, but not kegging equipment. Except keg o-ring kits. Kettles, burners, etc. are too expensive to stock at first.
And the most important one: Does he brew himself? I doubt he will succeed if he doesn't. Homebrewers expect advice, lots of it, free.