^ actually cars101.com's invoice pages do break out the destination charge in a separate column for a true "dealer's invoice" quote, and some sites do in fact list the invoice prices of the available options, eg: Motor Trend's summary page here.
(apparently invoice price is 60-65% of list for options )
But thanks for the advice on pricing. I tend to be somewhat passive and a take-it-or-leave-it type, so my negotiating plan, if I were looking at taking delivery from the dealer's inventory, is just offer the price I was willing to pay, somewhat determined by how long the car has been in inventory (which I assume can be accurately guessed at by looking at the VIN code's serial number).
Assuming I can get 2% under invoice for new factory order, I'm going to want most of the holdback for a lot queen that's been in inventory for months and months.