When I bought my bike last fall. I knew I was going to buy a new bike, hopefully, from a local store. I went to as many stores and test rode as many bikes as I could. Eventually, at one specific LBS, I paid for a fitting ($75) that was deducted from the price of the bike if I purchased from them. (I did.) Very happy with the purchase.

I wouldn't buy a bike on ebay. If you were very familiar with bikes, different models/makes, sizing, and had the tools/time required to wrench a bike, then eBay would be the place. You wouldn't really need an LBS anyway. But to think you are somehow going to undercut the LBS? They might not be in business the next time you need a test ride/repair/overhaul. I also see nothing wrong with looking for the best price and service and haggling about it.

For me, it was about service, fitting the bike, and feeling comfortable about the process. Sure you pay for it, but it is worth it.

SKM