Paul,
Previously I used to grow some castillejas although I usually planted them out eventually, I know one survived even after I had abandoned that part of the garden and most other plants had given up the ghost. Most of the seed came from Alplains. Margaret and Hendry Taylor still grow some both in their garden and in pots to give to people. Perhaps we don't see them so much as they tend to flower after the show season is over so not many people want to grow them.
Certainly it is good to see you promoting them
Susan