Hey Rick,
Khao Yai lies ESE from Bangkok, about where the "lower-lip" region of the elephant's head is, approx 70 clicks W of the Camboge border. My plants are jungle collected and are 'pure.'
There are plenty of P. callosum and varieties still in habitat but I do not know the security of those places. I have not personally collected from very many habitats, but I have seen several regional types that I believe are geo-specific. I doubt that they are exported in the same numbers as from the past, but this is only a guess.
If your question is about whether or not they are bred in cultivation and then sold overseas, I think they are collected and then sold.
While lumping them all together as a single species, I think they can and should be separated at some time in the future, if that can be possible. Whatwith CITES, I don't imagine that can ever be accomplished while the treaty remains in effect.