Some thoughts on running a business in general:
I own a home-based business (I edit novels, design books, etc., which I do online) and help my husband with his home-based business (a motorcycle shop, so his clients come to the shop). The success of both businesses depends completely on top-quality service at prices that fit the current market. It took us a while to get our prices up (we actually still get people deliberately overpaying), but we know now that customers are happy to pay the going rate to have their needs met (in the service industry, anyway).
Talk to your potential customers (which you're starting to do here, so good job). Do an anonymous demographic survey. Aim for at least 50 people's responses. Ask specific questions about their expectations of prices and services. Ask specific questions about their income. You may be surprised by their answers, and the survey will help you form a realistic business plan.
My thoughts as a customer:
I'll drive three hours to go to a good fish store with healthy fish, clean tanks, no bad smells, and dependable advice rather than going to the nearest (gross, smelly, diseased) LFS. I love that my favorite fish store is on Facebook, and I can ask questions, place orders, see pictures of fish and corals, right in my house.
My thoughts on dry goods:
I buy my salt at one of the big chain stores because the price is better, but if it were within about $5 of my favorite fish store's price, I'd buy it at my favorite store. I don't mind paying a little extra, but I don't want to be gouged, either.
My thoughts on equipment and supplies:
Give good advice about how to use that stuff (like plumbing parts or whatever), and don't try to stock things you'll have to keep in inventory for months on end. Do keep a few emergency parts like maybe some skimmers, pumps, powerheads, and heaters, to get people through a crisis.
The most important thing: continually review and revise your business plan.
Good luck!
