Dude! You so should buy it at another dealership. Call up the manager make an appointment to see him. Like your going to buy something from him. Ask him to come out and meet you infront of his sales man buddies. Say something like "[name] Dealership let me test drive my Nismo and i bought it cash, just thought i let you know how much you suck..."
or simply
"Do you like my new Nismo i bought cash?.." let him sweat an answer "See what happens when you descriminate!" (maybe throw in a B*tch at the end) and drive off
:stirthepot :
I almost did something like this to my local dealership when they didnt want to make a deal.$$ But since i picked another trim level they didn't have, i figured it wouldn't have been as sweet.
But i feel angry for you man. Good luck with purchase.