We Americans like to customize our belongings. The custom car parts business is a multi-million dollar enterprise. The same goes with our firearms. There is something special about having an object that was made just for you.
Mass production keeps manufacturing costs down thereby allowing the maker to pass the savings on to you. Conversely, if you want something made special, it will cost you. When you are talking about a custom pistol, rifle or shotgun, the price tag can easily run you several thousand dollars.