What is it that makes an Armani suit so pricey, Rolls Royce, or any other items made by hand. It is the fact they are made by hand. You lose the benefits of scale that come with mass production when you make things by hand. Are the benefits readily apparent? No, not always. I have handled a few very expensive guns that did not seem remarkably better than my wife's Kimber Stainless Target aside from a few features like checkering, night sights, etc. The difference in price could not be justified by a few additional parts.
Are custom or semi-custom guns worth the money. It just depends. The value of the guns is more than the sum of their parts. Can you get cheaper guns that are as good. Maybe, but probably not. Now that is not to say that you can't get cheaper guns that will perform as well as you need them to perform. For example, do I need the 1" at 25 yards for Wilson Combat CQBs or 1.5" at 50 yards (normal being 2.5" for some models that can be made more accurate for more money) for a Les Baer? That is a really cool feature, but I can't shoot that good and for a combat handgun where my shooting distances will most likely be 10 yards or less, probably much less, that sort of accuracy is unnecessary based on the cost for the products, but I think I will buy the guns with the best accuracy and reliability I can afford. I just might have to shoot something at 50 yards some day and I will be sure that my gun can do it.