The main reason why Rolex Milgauss are expensive is because of the craftsmanship and the materials used to manufacture a single Rolex Milgauss.
Some of the details in design and quality are not visible to the naked eye. For example, the Rolex Milgauss Twinlock crown that improves water resistance is not visible, but the ingenuity of the system and the engineering are exceptional. Wearing a Rolex Milgauss, you can sense the unique level of quality inside the watch. Even the way the crown glides when you wind the watch is smooth. Only a few watch brand provides this ultimate sense of quality and luxury. To achieve this level of quality, Rolex, maybe more than any other watch brands, is over the top regarding quality control. Rolex wants to control every aspect of the process.
Rolex SA used its own research labs located in Switzerland. All the components are manufacture by Rolex SA. The watch company does not buy third parties watch parts. To this extreme, Rolex has its own foundry to produce the metal used to manufacture their watches.
Rolex produces its own stainless steel 904L called Oystersteel, and also produces its own gold. Every movement bridge, wheel, gear, watch case, crown, and dial is made of the right material that has been carefully chosen and continually re-evaluated to ensure its durability and flawless aesthetics. It is an essential factor to create outstanding timepieces, though it comes at a cost.
Rolex's bezels are the most recognizable part of the Rolex watch. Rolex is also known for its Cerachrom, a ceramic with unique quality. Many Rolex bezels have become iconic.
With all the right materials, Rolex craftsmanship also has a cost. To ensure the highest quality, all Rolex Milgauss watches are manufacture in Switzerland by master watchmakers who are trained by the company themselves. There is no outsourcing of any aspect to cheaper countries or lesser trained technicians.
The process of creating the Rolex Milgauss watch, the level of qualifications required, and manufacturing location in Switzerland, are all factors in the cost of the Rolex Milgauss. The quality of the end product justifies the cost. This is one element that explain why Rolex Milgauss are expensive