Cobalt -
Maybe only 5 custom makers in your world, but every one of my 20 or so customs are real customs, and I have many more friends whose personal craftsmanship I am looking forward to patronizing.
Every one of the custom knives I own involved me personally in the design, material selection, and ultimate presentation. And every one of them was created from the ground up by the maker, and if embellished, marked by the engraver. True, they were expensive, and took a long time - but that's what makes them truly valuable, and what makes a genuine custom knife different from knives produced in any other fashion. To include semi-custom, customized, and most patterned knives in the same category is incorrect.
Call Blade Rigger and ask them the difference between the two marks their knives carry. James will not mark a Blade Rigger knife with his JSP mark, even though he himself does all finishing, and is involved throughout the process. Only when the knife has been his personal project, start to finish, will he consider it truly custom, and appropriate to mark as such.
If you call John Greco, and ask for pretty much any knife out of his catalog, he'll just grab one of the four or five of that pattern he has sitting on a shelf, slip it into one of the general purpose, plain black sheaths that his wife has made, and ship it out. Regardless of the fact that his hands fabricated his design completely, the knife is not a custom knife, as John just bangs out dozens of the same patterns, and inventories them, rather than making each to order. It's a distinction that he reflects in his pricing - very few of his handmade knives go off at over $135.
Ask the makers if their knives are customs. If they are men of integrity (and most knifemakers are), they'll be happy to tell you exactly how their knives are made, and if they consider them "custom". This discussion has been had many times, but until the Guild changes their definition, I'm not changing mine.