Dab-Nabbit

Hi everyone, I'll keep this as short as I can. I need some advise with a problem I've got with my A3, a few months ago my timing chain tensioner fail which caused some pretty serious damage to my engine. Since then I've had it reconditioned. However after reinstalling the engine and running it, it looks (with almost certainty) that the valve variator needs replacing. Whats my question? How much would it cost to get that changed and if not, how difficult would it be to sell the car with this problem? Just as a side note, the car is a three door Black Edition with full leather interior and satnav its also (apart from the obvious issues above) in perfect condition inside and out.