There are a few other growers in the US who have them in ground as well, but definitely the influx of cuttings is from people getting them from overseas and then jacking up the prices.
I think about 1/3 of what I have I’ve gotten from him. He has fed my addiction mercilessly . He has great notes and recommendation. We may be several hundred miles apart but our climates and growing zones are very similar, I much prefer stuff that comes from your area or colder. It may just be a theory but I’m pretty certain with the way things evolve, plants are no different. They adapt to their local climate and begin develop characteristics needed to thrive.