I say either of the red ones are good options, since they have less mileage than the white one. If you offer them around 24k and get it for that, it would be a great deal on the one with the nav.
Have you also looked at the private classifieds on this forum? There maybe people selling their 09-10 with your preferences. Check it out.
Cars for sale (Private Classifieds) - Nissan 370Z Forum