Ask your customers and you will end up with a shop that is open 24*7*365, has everything ever invented thought of or fantasised about, 1 day after either manufacture or harvest.
All hops, malt and yeast are discounted by at least 50% under cost once they are a week old.
You will need a store within 1km of every customer.
You will need to be cheaper than any bulk buy, give free freight and able to make stock appear at their house with in 60 seconds of their pressing the enter key and make dam sure they get what they thought they wanted even if its not what they ordered!
Knowing everything there is to know about brewing, wine making, distilling, wiring fridges, making brewing equipment... is an obvious prerequisite.
OK 20 odd years as a retailer left me a bit jaded. Amused the hell out of me to see WEAL giving business advice, the king of bulk buys, getting hops in from the UK to save a couple of cents, in fact doing everything possible to kill off LHBS's (unless they are KegKing), but in this case there might even be some truth in what he says - there is in what he does, that's how your customer base (well a fair sized section of them) will act.
Based on experience, to make a living out of AG you will need to be in a very large city, even then it will take up much more of your time than will the other customers (K&K+, Distillers, Cheese makers...) who will be the ones paying your bills. There simply aren't enough AG customers to support more than a very few specialty stores.
I recommend you think very carefully before asking customers for advice, the advice you get will help them not necessarily you.
Mark