I would look and see if there are the same speakers on Agon listed as demo models and see what other dealers are asking for them as demo models. Also look at used models and figure you will pay a bit of a premium over used because of the manufacturer's warranty. I don't think there are ahrd and fast rules. It all depends on how much you want them, how good of a relationship you have with the dealer selling them and how much hardball you want to play before getting them. Also, on the manufacturer's warranty, does the clock start when you purchase them or did the clock start when the dealership bought them and you are getting the remainder of the manufacturer's warranty (i.e., if they come with 5 year warranty and they are three years old, you are getting 2 more years of warranty coverage)? If the latter, obviously pay less of a premium over a used model without warranty coverage.
