If i'm not wrong its about 8k or something to put an east bear kit on. I could be wrong though, its been a long time since i've looked into it.
imho, keep your gt/gtt looking the way it is, and if you want a body kit, get something that was made for gt/gtt, keep the authenticity of it. It'll also be alot cheaper. think about 2k for sides/rear including fitting/painting?
when i first got mine i just wanted it to look like a gt-r. but after i'm so glad i didn't. mine just has a basic impul sides/rear on it, and its been lowered onto some 18" wheels. you could do something like the altia kit, very popular, so if you sell it should be all good
it'll make the gt-r that much sweeter when we finally get it