I'm in the "Make my Own" arena. Personally I dislike sheath work the most of any aspect of knifemaking, but I am also so anal about my knives being "just right" that I can't accept a knife with my name on it going out the door without a sheath that does not "match" the knife in every aspect. To explain, I've tried a number of times over the years to out source sheaths, and one of two things is generally the result.....
1. I get a low quality, light weight sheath, that I wouldn't put a knife purchased at Walmart in.
(I've seen far too many very nice knives that were sold with a crappy sheath..... or vise-versa.... kinda like buying a Cadillac with retread tires.....they just don't go together)
2. IF the sheath meets my required "quality level", it simply doesn't "match" the knife, meaning that it is very obvious that the knife and the sheath were produced by different individuals... another situation where the two things simply do not go together.
Neither scenario is acceptable to me. Therefore I just "suck it up" and build my own sheaths, whether that be leather, kydex, or whatever.
That being said, there are some very fine sheath makers out there, and while many makers have great success, and are very happy with their products, it's simply not something I do with my knives/business.
One of the things that my business has been built on over the years is that folks know that when they order a knife from me, EVERYTHING, including the sheath, is done by me, and that's a trust that I'm not willing to jeopardize. At this point in my career, even if I could find a sheath maker that could "match" a sheath to the knife I made, I'm not sure I would do it.