In Islamic teachings Hirz is considered a protection against evil and Jinns.
There are many different ones which have different effects but the most famous and useful one is the Hirz which has been narrated from Imam Al-Jawad.
There are different conditions for preparation of this hirz. The person who writes it, the type of paper they use (should be Gazal’s skin), the container it must be kept in, the type of pen and ink it should be used and more.
The reason it is more costly is that cost of skin and the silver container is included.