If the parts the make up the NOS parts watch are all 100% original Heuer, from the correct era (eg: not later made service hands), and the case and movement are also from the correct era, so everything is correct, I can't really understand why this is something which is considered as not desirable and to be sneered at. We are not talking about an old master painting, we are talking about a factory produced item, where all the parts (movement, dials, cases) were made at different mass market factories across Switzerland, only to be assembled by Heuer. So a Heuer factory worker or a Heuer qualified watchmaker made the watch. I am not sure I see much difference. It's the same watch in both cases, with exactly the same factory parts, that is the reality.

However, then comes emotion. If you value the fact that the watch was made 40 years ago and has sat in it's unused state for 40 years in the basement of a jeweller in some little German town, untouched, a little piece of history, then yes, maybe that is worth something. I can more easily understand the value of watches that have some history, let's say that they have been worn by a racing driver (even an unknown one) obviously makes a big difference in value. And Buzz Aldrin's watch worn on the moon might be a little more expensive (by $1m?...not exaggerating) than some perfect NOS pre-moon Speedie (exact same model) kept in the safe of a dealer in Bahrain. I certainly can't argue with that difference in valuation!

If we look at cold facts, the NOS and the assembled watch are identical so should have identical values. On emotional terms you want something that was made in a certain era and has some history associated with it so that affects the value massively. I guess between these two extremes everyone sets their view of the correct price....