I guess I took a different path. I acquired all of my parts (from Brownells and Caspian, NOT eBay!

) and decided on the gunsmith. Any gunsmith who wanted to take issue with my parts (Caspian slide and frame, Heinie sights, Kart barrel, mostly Ed Brown small parts with a couple of Wilson ones) got immediately dropped from the list of "possibles" regardless of who he was or what I thought of his work. In the end, I got what I wanted.
I have no problem with a gunsmith supplying parts if I'm ordering a "package" gun from him but if its something that I've specified, then I see no reason why I shouldn't supply the parts
if that's what I want. After all, despite what a lot of gunsmiths like to think, if I pay for it, it's
MY gun,
not theirs.
I actually had one gunsmith that I contacted tell me that, even if I supplied the parts, he was still going to charge me the difference between dealer cost and retail cost on each and every part that I sent him. He
wasn't some amateur, either, but was (and is) a Guild member and nationally-known pistolsmith. Needless to say, he got dropped from my list.
But, to actually answer the question, it really doesn't save you any money to provide the parts yourself. Someone, either you or the gunsmith, is putting in the time to order them, unpackage them and organize them. Even if you CAN get them at dealer price, what's your time worth? If you judge based on the rates charged by my employer, I'm LOSING money to order my own parts! For every part on a 1911 ordered from Caspian and Brownells, the difference between retail and dealer is probably only a couple of hundred dollars or a little more. If I'm dropping $2K (my personal upper limit) on a pistol, a couple of hundred doesn't bother me much. If saving that much is significant to you, then you might as well buy a Wilson, Brown, Baer or Nighthawk and save the true custom pistol for another day.