Sounds like the guy is dreaming. If he thinks he can just let a car sit and go to pot and not have it lose major value then he obviously has his head in the clouds. The car is probably going to rot there.
Where in az. is it? Don't worry, there is no way in hell I would pay 20k for that car, gnx or not. 20k goes a long way into my racecar, not some crappy, resto project. Just my 2 cents. Buy a nice gn with that money and have some left over. I am the same way with my wife though, I give her all my money for the mortgage and car payments(we both work) but when it comes to these cars, I do what I want.