oldsmobum

When they are gone will the internet fix your wheels? Not everyone is inclined enough or cares to learn how to work on their own bikes, and they are far more active in advocacy than most online shops. NO ONE in the bike shop is getting rich off of you. That being said, the retail climate is what it is, and those shops that insist on whining about it instead of adapting or try to go head to head with the internet will be gone shortly. Do you tip your server in a restaurant? Not everything is dramatically cheaper online. If you like the shop, and the price isn't too much higher, buy from the shop and consider the few extra dollars the "tip". Every bit helps.

The price differential is multi faceted... There are three big ways these outlets get the parts cheaper:
1. Distribution channels. Shimano Japan treats Shimano America just like a separate company, and they sell product to the American division marked up. This happens a lot with Japanese companies, like komatsu (which my dad works for) Europe sources parts from Japan not Europe. This is what the local rep explained to me.
2. Manufacturers discount. Some of these retailers qualify as a manufacturer, by owning a bike line. This way they can order parts in higher quantities and resell them at lower prices.
3. They buy from manufacturers. Often manufacturers like Giant will over order componentry. Online resellers will buy this stuff at 70% what the manufacturer paid for it, further deepening their ability to discount.

None of these your bike shop qualifies for. Often the wholesale price is higher than the online price, so they would never be able to price match unless they wanted to lose money on the deal.

Most of these channels are not supported by Shimano, and they technically do not carry a warranty. Caveat emptor