I have a nexus 7 and half the screen is not the right color any fix for it.
http://www.overclock.net/content/type/61/id/2225114/

Buy a new one.
no its a 2012 8gb model no warranty on it. this thing never gave me a bit of trouble always ran great, still runs great even with the screen problem.
whats it worth if I try to sell it in its condition.
You could try taking it apart and seeing if any cables are loose, but other than that, at this point it's probably cheaper to replace than repair