What a "top smith" will and won't do is contingent on a lot of variables that only they can speak to, as they are almost all self employed and answer to themselves as boss.
But here's one to ponder...
Many (dare I say most) of these guys are one man shops, or maybe have one apprentice. That means they can only make money when they themselves stand at the bench and do work and they don't have 20 guys out in the shop compounding their productivity. So if they have had bad experiences with certain mfgs frames being out of spec, or odd in some way... they know that what might take them 30 min. on a Colt or Springfield frame will take them 50 min to do on a XYZ frame. If they list $x for that particular task on their standard price list, that means that they make less money on XYZ, or they have to "insult" the customer and explain why they have to pay a higher price, or he can decline the job in favor of catching up on the 10 others he has waiting in line that have frames with which he has had consistantly good past experience. Then when you consider that the smiths reputation is on the line if XYZ guy starts bad mouthing him all over the internet, you can appreciate why they may list "I only work on.... frames" on their web site.
Honestly, when you look at the cost of shipping a handgun, and then add in a top smith's labor and quality parts, the price of the base frame becomes less and less of a % of the total. So it's understandable why their might not be 100 guys beating on the door to have work on XYZ frames.
Now if your talking about a base frame for a DIY project, that's an entirely different conversation.
