I would pay retail (or buy a demo unit) if I wanted to demo the unit at home, and especially if it was a high demand unit with high resale value (such as McIntosh or Audio Research). Like many audiophiles, I like to try different things, and dealers don't stock many items, so I just end up purchasing used here, and if it doesn't work out, sell it again. Of course, somebody must be buying new in the first place.
The trouble with audio is that you can't just walk into a dealer, listen to a system, and know how it will sound in your home. One of the local dealers does well with cash flush people looking for gear that is high end to show off in their $500,000 condo, those guys aren't picky as long as the gear is flashy and has a "name". These are the same guys that had an incredible Dynaudio C4 playing on a McIntosh MC275 amp: terrible combo (no juice for the speakers) not to mention the listening room was a big, square cinder-block room with no acoustical treatment whatsoever.
Dealing with audiophiles, many are much pickier, as gear matching can be finicky, and we are often looking for brands other than the big ones that are easily found. The other thing: I am no audio expert, but find myself more knowledgeable about gear and system matching than most people at a dealer. They seem to only know what they sell, and if you ask how your source might match with that preamp they are selling, they give you a blank look. They have to run a business, I get to fool around on the forums, read threads, and see what is working for people.
With that said, if I had money and had a great local dealer who took care of me, I wouldn't hesitate to spend my money with them, at full retail. I work in retail myself, and greatly value service and knowledge. Saving money is nice, but often isn't worth the hassle, and can cost you money in the end. The wrong gear at a discount is still the wrong gear. I do think it is unfortunate that so many customers place monetary concerns as their first, second, and third priorities when buying items. I think it is because we Americans buy way , way too much stuff. If we only made a few important purchases, things that were really dear to us, instead of buying lots of cheap stuff, we would be willing to pay for service, as the purchase would bring us years of enjoyment.