We have a relatively simple way of dealing with an Internet shopper. We point out that we will cover the Manufacturer's warranty, meaning we will deal with installing/replacing/returning any defective unit we install. We point out the additional cost of shipping added to the internet price. We will match MAP of any item we sell.(We normally price items between MAP and MSRP) If this still is not enough to convince a "wipe" (great term btw) we will install the piece for them as long as it meets our design.(IE brand and model specified by us.)Of course, warranty is now up to them. If they still want to haggle, we explain that we are not the A/V dealers for them and recommend someone else. We do this all very politely, of course!
Hope this helps someone..

Mal