I should probably elaborate on how to talk to a store - there are a few points you should keep in your mind before you talk to them:
1. Are there others in the area selling the same product? What price do they have it listed for? Any sales going on? If yes to any, that's great, you can now let them compete and not be able to say things against unauthorized sellers.
2. Find competing products from other brands - maybe Onkyo? Yamaha? Would any of these actually be fine for you instead of that specific Denon model? If you have some flexibility, point out that you want one of three 2/3/4 receivers and that you have compiled prices from various stores in the area. Tell them that if you don't get a good price on it, you'll buy the _____________ model receiver from _________ store.
3. Look up some information on when the receiver was launched and when the next ones are coming out - will they be wanting to clear this one out within the next few months? If so, definite point to make.
4. Other than these things, you need to keep in mind you don't want to be an ass, say some nice things regarding why
you want to buy from them. (customer support, location, friendly salesmen, etc.)
5. Avoid the expensive cables at all costs