What is the most expensive cat to buy?

Could you elaborate on what factors determine the cost of a cat, especially when considering which breed is the most expensive to purchase? Is it the rarity of the breed, the pedigree of the individual cat, or perhaps the demand for that specific breed in the market? Are there any particular breeds that stand out as being particularly costly, and if so, why? What advice would you give to someone who is considering purchasing an expensive cat to ensure they are making a responsible and informed decision?