For a higher end car, custom colors work out well. Those types of cars don't really depreciate. For a car like the Z, it will be neat for the first owner, but if you paint it something crazy, it will make it hard to sell later (I know everyone says they'll keep the car forever...but how many vehicle listings say "Don't want to, but I'm selling my baby"). Plus, it's going to be super rare for a paint color to add value to a car.
What would be an acceptable option price? You'd realistically be looking at a high 4 figure to 5 figure price for custom paint, as the car has to be pulled off the production line, and painted separately from the other cars.
Bottom line; you want a custom color? Get a wrap. You protect the paint, and you get the color that sets you apart from the crowd.