Andy's and Santa Barbara Orchid Estate have both had them in the past, though they are not currently listed. Both of these vendors tend to have things in stock but in such limited quantities that they don't list them on their sites, so it may be useful to reach out to them directly to inquire if you have not already. I've had luck with that approach with both of these vendors in the past.
Several years ago, it seemed like several US vendors had these for sale, but at the moment I'm drawing a blank on exactly who had them. If I end up recalling some more, I'll try to check around and/or let you know.