examples?
Not that you're wrong, I see IWB and pocket kydex holsters for .380's in Amazon for 19.99 and up. A kydex for a Swamp Rat cost me double ten years ago.
I had to ship the knife for them to make it - more $$ - they had no form, it was custom one at a time work. And there is the rub, you can buy plastic guns for forming kydex, but not knives. So a kydex maker can make ten, twenty, a hundred and it will all be good work if that's his standard.
Make sure the mag catch is fully extended . . .
But a knife, no. It's still custom, as there are hundreds of new knife designs being done every year. Guns, not so much. Resin knife forms don't suffer a lot of hot kydex forming, either. Too flexible.
So, with knives, you shop and buy a kydex sheath with it as that is the one mass produced sheath available at a cheaper price. That is one of those hard to justify things for some knifemakers, too. No sheath at all is their preference. Hence one of the attractions with ESEE, you get a sheath with it and they are well made.