I have to qualify what I am saying from lessons learned by my dumb @$$ mistakes and also my clients not so good experience.
Much of what has been said above is to be taken and paid attention to as the above posters have been there an learned the hard way.
Just also keep something in mind and this is with me also as I am as guilty as the rest. Many, many of the gun issues on forums are actually operator issues but you do not hear that part. Being in retail I hear how "screwed up" this or that was and in reality
operator issue.
I retail the higher end 1911's, the top three shops, and have been dealing with the one man shops for many years. I have learned from making many "price" choices over "value" choices that "best price" in not the driving factor in a well made product, craftsmans work, or good value.
Again, what I say is from me making
@$$ mistakes and watching countless others do the same.
Search for best value not best price. (part of your cost, the search)
Now qualify it with this, production pieces are good and work within what they were designed for. Basic function. Productions guns are from companies that produce 30,000 to 50,000 guns a year so there is very, very, little time spent on them. Check the ATF website for quantity produced.
If you want anything else will cost you. Everything has a cost because if there is a discount your undying gratitude has nothing to do with it.
Cost is not only money, cost is actual time to build, length of waiting list to get to your project, experience, skill, research, and a few other intangibles. such as trust, reputation and integrity.
Quality of components; time invested in the building of the product; skill level of the craftsman; reputation of the shop; and a few other things.
There are components made to standard specs, then there are components made to the highest level of quality. Which cost more. What is the best value. Production guns make good starting points and work well but what does the craftsman you trust say. I am certainly not going to invest $3K worth of skill in a Rock Island, (not to be confused with Rock River). Caspian for example makes many levels of frame. Some average and some higher quality.
Others say you are paying for a name, so what. The name and reputation is earned, not given. What till you resell the no name or multiple work by various maker or craftsman piece.
Now factor that on skill level of craftsman, One making $5 will not do the job of one making $50 an hour. A comparison is a doctor who just got his license and was at the bottom of the class, then a doctor who graduated top of his class with years of experience. Who do you want for your brain surgery. Your choice. (someone mentioned to me on another forum doctors get paid the same when on call so this was a poor analogy, it fits for comparison)
The top three i.e. Wilson, Brown,and Baer only use their parts for reasons such as proprietary reasons, trust, follow up service (for example Wilson will service 2nd and 3 owner guns; You have to trust the parts you use if the gun is 20 years old and then how do you know is some other lugwrench gunsmith has done something to it).
If you do not like what each of the name brand shops use then your choice is go to a one man shop. Many of them will not work or use parts they do not trust.
Some costs are variable as well as intangible in nature.
Alex Hamilton, who writes for Handgunner stated words to the effect and I should have the context correct, "to be a good successful gunsmith you have to be a good businessman also."
So keep in mind will the craftsman working on your treasure be in business tommorrow or two or however many years from now when your "treasure" is done.
If there is a waiting list, there is a reason.
Remember what I mentioned about a "discount" there is always a reason.
Just some thoughts from both the retail and consumer perspective.