Part of the "dicker" factor is:
:ani29:: final price for "packages" of add on's--a thousand or more should receive some kind of discount
:ani29:: Negotiate labor charges for the install.
:ani29:: Add on "setup" and "freight" charges.
It's all between you and your dealer. Some are better than others on the above.
I do have a problem up front with dealers that post a certain price, and then begin to "add" on all kinds of charges. I will not deal with such a place.
Caveat Emptor