Not really answering the question, but it may not be the LBS's fault.
I've noticed a lot of suppliers/distributors have a variable pricing system based on the amount you order. i.e. if you are a larger shop/online retailer you get a preferential trade price for buying more.
Add to this suggestions that the larger companies deal in 'grey' imports and sell 'OE' kit and it's a wonder any small LBS stays in business. The fact that the headset is more expensive there may be because it costs them more and they need to charge that price to survive.
I often heard it said that you could become very busy if you sold things at the right price but not actually cover any of your costs (and therefore stay in business very long).
Where the LBS wins is the ability to get something done then and there as said above (although reports are that a shortage of bike mechanics is putting paid to that) and the fact you can ask questions, get advice and physically look at the products.