I've met Ken at the EOC at the scientific lectures, I don't want to advance me too much but I don't think his interests and goals at the moment include amator collections. Now maybe he's more open for people in the USA. He's in charge of other things too and maybe don't have the time, he was also there on business job in the labs at Jodrell. I'm more interested into his current work on rationalising the genus than plants he may trade as an herbarium director. He's the only one working on this issue at large, other labs afaik are on academic and narrow aims like variations of DNA on the commercial species.
On my side, I've found between some private collections and shops 16 species (14 or 15 in da house already) in Europe and I'm in contact with botanical collections for rarities they have (exchanges to make). And I' have not even yet contacted the vanilla conservatory depending from France, one of the 3 with the whole genus.
The Clouds Orchids suggestion is a good one, got to see if I can set up a group buy to reach the 500$ mark for non USA… not to mention the fight for importing to EU (damn papers…) :-/