Thanks all for feedback. Indeed, since I am fond of standard lenses, I am very tempted to add this very special one to the inventory (the last two additions were the 50/2 AI and the Zeiss Milvus 50/2, both second hand, yesss). Problem is, I am not even sure to use it more often, or with more satisfaction, than either of the two aforementioned lenses that only cost a fraction of the Noct. The 50/2 buy is all Fons' fault, by the way, and I do not regret it. The Noct is certainly overpriced, if only imaging qualities matter. We're paying for the legend.
Buying and reselling seems a safe option though, since the likelyhood of any similar MF lens to be produced is close to zero - Zeiss' closest matches have been released twice (Otus and Milvus versions), Samyang released a 50/1.4 that is not bad...
And concerning the MF standard lenses, I have yet to find a long nose 50/1.8 AIS.
I still have the Neo-noct as an option (a second hand one is still available, it seems...), but at 1100€.