I don't think the value of the collectible kits will start dropping until the people that got into model rocketry in the 60's and 70's start dying off in large numbers.
I seriously doubt the values will drop much before 2040 or so, if ever.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !