Hopefully the irony isn't lost on anyone here that this forum is sponsored by a really great e-commerce site that is, by our logic, killing your local bike shop.
If you find a LBS with a good mechanic, spend $$$ there by all means - but in my experience (often, but not always) the better the "stuff" in the shop, the less reliable the mechanics are. Probably because the store management is chasing sales at the expense of substance.
Distributing cycling goods through a LBS is woefully inefficient. The LBS's cost for many components and products is above the price that the major online retailers can SELL them for. LBS's can't compete on price. It would be insane for them to try. And I'm sticking by my story that it just doesn't make sense to pay more for something than you need to. If you've got extra money, make charitable donations...(of course you may decide that your charity of choice is the local bike shop, and that's entirely your business).
Every time you spend money on something you are encouraging the seller to offer more of it. If you want $6.00 tubes - buy 'em. If you want $120.00 jerseys - buy 'em. But if what you want is great mechanical and race support - buy those same tubes and jerseys online at half that price or less, spend the money you're saving to in shop fees at a LBS with a trustworthy mechanic, and encourage your friends to patronize "your" LBS. That rewards the LBS for its strengths and I'd contend that it does just as much to keep the shop in business as it would if you deliberately overspent on cycling goods. It also means that you've got a real relationship with the shop, and you're getting a better-maintained bike, which will last longer and be more fun to ride. And if those Oakleys catch your eye one time that you're in and you simply can't resist - well, you can still feel pretty good about that.