Like someone mentioned earlier - check out some online realtors just to get a ‘ballpark’ number. I know CarMax was offering me the most for my car and it might be worth just to take it there and see what they offer you - the estimate is good for 7days and if you are happy with it - they make it really easy - sold 2 of my cars to them in the past. Regardless GLWS - honestly it might be the best time to sell if you are going to be without a Z for a few years - since the new Z will be coming out along with - give a few years and the market will be back to normal thus we can see what the used market is like for these cars.
Anyway - GLWS