Mr. Coral is an excellent example, but you have to bear in mind that the guy who owns Mr. Coral has a good deal of experience as an entrepreneur in another industry. He's done an exemplary job of developing and implementing a good business strategy, and I really hope he does well because he's an inspiration to others of us who are entrepreneurs in our own way. And, by the way, he was a hobbyist first, and saw a way to turn his hobby into a job (that I hope he enjoys).
I think part of what makes Mr. Coral successful is that he essentially operates three different stores. There's the retail store in a small strip mall outside of town where rents are probably comparatively low. You can go into the store, get real advice from real people. Sure, they want to sell you something, but we all know to take what the LFS says with a grain of salt. They run in-store specials now and again, like buy 2 get 1 free, but you don't know the specials until you show up. This draws locals into the store (he definitely attracts some people who make a significant hike to get to the store).
Then he's got the website. He runs different specials on the site, and everything is WYSWYG.
Then there's eBay. Again, WYSWYG. He draws people into eBay auctions with low intro prices and lets people bid up to what they think is a fair market value. Plus, he gives you really comeptitive prices for shipping.
As far as I know, he doesn't cross the inventories or, if he does, he's got some really good inventory system in place to keep from double-selling an item. Plus, I think his cherrypicker does a really good job of picking outstanding specimens, even if they're not Ultra-Rare, Limited Edition, or tagged as ORA or Tyree or some other price-hiking pedigree. I've never had a problem with any of the stock I've bought from him (corals, fish, or inverts), so I can't say much about shipping / DOA / refund or replacement situations.
I live about a half hour from the store. I've bought stuff from him both on eBay and in the store. I'm probably in the store once a month or so. You can go in there and pick out some tiny frags for $5.00 each or you can buy enormous and beautiful specimens for big bucks, and everything in between. I don't doubt that his initial investment in equipment and stock was significant, but he definitely is doing something different than everybody else.