The reason why NJS parts are so special is because they are made from an unearthly ore extracted from a meteorite that crashed into the courtyard of the Byōdō-in Temple at the pinnacle of the 12th century Battle of Uji, which started the Genpei War.
The Samurai and Warrior Monks who survived the battle then used that ore to make swords and armor of mythic strength and lightness, and were said to be imbued with the speed and grace of the hawk, while possessing the strength and power of a Dragon.
Over the centuries those sacred artifacts were lost, recovered, forgotten, and reforged, until eventually they had disappeared entirely from the annals of history and all but the vaguest oral traditions carried on by the descendants of those Samurai who wielded them.
They were lost, that is, until 1945 when a Japanese submarine crew discovered a sunken 16th century Japanese warship, and the trunk of armor and spears contained in its hold.
Transported back to Kyoto, the true power of these treasures was being explored, and they were believed to be the key to winning the battle in the Pacific. Japanese scientists and scholars were on the razors edge of unlocking the secrets of the ore on August 7th... and then the war was over.
Three years later, Keirin was born.
The ore from that celestial stone was melted and reforged; into stems, and hubs, and cranks and frames. Only a scant few kilograms were available, and so only the greatest grandmasters of framebuilding were allowed access. For generations, when a Keirin rider retired or was killed in action, his frame was melted and forged anew, the steed that would grant a new rider the speed of that hawk... the strength of that dragon.
This is the reason NJS parts are so rare. There is no limitless supply of that ore. For you to buy an NJS stem, another must have lost his. For you to enjoy those NJS toe clips, a Keirin warrior must go without. Your seatpost once ran red with the blood of a Feudal Japand, and your LeveL frame made impervious the heirs of kings.
Do not take these things for granted.
Don't even get me started on Campagnolo.