What of cost goes into manufacturing cartridges?

The largest part of the MSRP is the labour.

The only people with accurate cost data would be actual cartridge manufacturers, and they undoubtedly regard such information as proprietary. No company shares product cost data on a public forum.

To what practical uses could you put such information? Offhand, I can only think of two:

1. You plan to manufacture cartridges yourself and are trying to develop your business model. (If that's the case, why would you expect help from companies you'd be competing with?)

2. You want to have a basis for griping about the prices of cartridges. (If that's the case, why should any cartridge manufacturer assist you?)

Trolling, are we...?

What are you referring to when you say "tiny needle" , is it the cantilever + tip, or only the tip?
The materials used might be as expensive as the skilled labor. The tips are frequently very precisley calibrated special shaped diamonds. The cantilever are usually a precious material as well in many high end carts, Ruby, Diamond, Boron etc. The the coils can be pure gold and magnets platinum. Sounds more like a good piece of fine jewelry than audio. Sometimes the bodies are gold or some other gemstone material. I don't know much using these rare and expensive parts really contributes to sound quality, but it helps to justify the very high prices some carts sell for. Mark up may be expensive as well, as it usually is ultimately buying retail. I am not griping I buy what I can afford and generally have no desire to get the more exotic and pricy ones. How others spend their money need not concern me.