Another way to rephrase the OP's question would be, 'Why doesn't someone take advantage of this market opportunity?' Heck, as some have suggested, couldn't a typical geek buy retail from Newegg, resell at sub-Best Buy levels, and still make a profit?
Well, perhaps, on a very limited scale, I suspect. Once you try to expand beyond a small shopfront, you need to rent a serious amount of property; find, assess, and employ (semi-) skilled staff; come up with advertising campaigns (and budgets); etc etc. I'm very curious to see how well the shops that do offer relatively reasonable prices (for brick and mortar) and fairly knowledgeable staff will fare once Best Buy is the lone national consumer-electronics chain. How well are Fry's and Micro Centre doing these days?
There may be an inherent problem in this market: the sort of customer who knows both products and prices well (ie geeks) will almost certainly shop online if they can help it, since there's no way any brick-and-mortar retailer can compete with online price efficiency, and geeks generally don't require 'expert advice' from on-site staff. That leaves the vast majority of consumers, who will patronise Best Buy so long as it provides better service, selection, and prices than their direct physical competitors (and when your competition was Circuit City, CompUSA, and The Wiz, well...).
