By the time you get to the dealer, you have already guaranteed yourself a bad experience (unless your goal for the day is just a test drive). The key is to contact multiple dealers with the same fairly specific request. You'll be passed on to the most desperate salesperson on duty, because no one wants to be in a competition. The desperate salesperson at each dealership, however, will know he's in a competition, and he'll act like it. If you're especially brutal with the poor bastard he'll throw in free delivery, and you'll never actually have to go to the dealership.

EDIT: I see lots of CarMax recommendations. Maybe they've just automated the process I've described.