Let's face it the car is a KMS with a CSX#. The registry and CS classifies these cars as component cars. Collectability will be determined in 20 years or after CS moves on. I (opinion of course) don't think the 40th A car is any more desirable than any other 4000 ally car.
I would determine price this way, what would a comparable KMS sell for then add how much you would pay for the CSX#. That will be what the car is worth to you.
With any luck the car will get more valuable however these cars seem to hold value so buy it to enjoy and not as an investment.