If you think asking for discounts from audio retailers is wrong; I don't agree. What about those people that ask for a discounts at a Dentist office?
So if you were not aware of the sad state of medicine in the US, there are two prices when you go into a Doctor's office. The Cash price, and the price they charge your insurance. So yes, you do get a discount when you pay the whole bill yourself and not use insurance. In fact, you might be surprised to learn that some Doctor's offices are cheaper if you pay cash vs paying your insurance's copay (especially Dentists' prices for fillings, etc.) --- but this is entirely off-topic.
Back to the OP, and Mike. It's capitalism all around, period. If we had one price (like Saturn Cars, etc.), then we wouldn't have the potential for significant profits. I say "potential" because many businesses don't make it and thus their potential is gone and sadly, everyone loses in the end.
I had a dealer friend tell me that he refused to sell a piece of gear that he had in stock to a customer because the customer asked for a 10% discount and he "didn't like the way the guy asked" -- I guess he was just having a bad day (both of them really). The dealer friend said the customer nearly broke down in tears because he expected at a minimum a 10% discount and just to teach him a lesson the dealer refused him entirely and told him retail or the highway. I didn't ask for more details, but I suppose the request was made in a rude way; it's also possible that the two just didn't hit it off and the dealer was being a jerk.
I sometimes hate making purchases just because of the bs I have to go through -- even with established relationships. As a consumer, all I want is to not get "monkey raped" as Mark so delicately put it.
I also have another dealer that has a great trade-up program. As long as the gear you're buying is twice the price of the gear you're trading in (that you also bought from him), then you'll get 100% of that towards the trade. So say you paid $10K for a DAC and want a $22K DAC, you'll just have to pay the $12K difference (within about a year -- you can't come to him like 5 years later and ask for this kind of trade-in value). I consider that when discussing price, so there are a lot of variables you should consider when negotiating a price. Establishing a relationship with your dealer is very important.
It's not disgraceful to negotiate, but it should be done in a respectful manner; don't demand, and don't expect the world. If the seller doesn't reciprocate, take your business elsewhere if you can't live without your discount -- but make sure you're not the unreasonable one.