Answer: After some searching, I was only able to locate sources in the Netherlands and the UK. In so doing, I encountered several different barberries called Apricot Queen -- including B. lologensis var. Apricot Queen' and B. chanaulti "Apricot Queen" but still no B. darwinii "Apricot Queen".
I then checked the federal regulations with regard to the rust disease with which certain forms of barberry are associated and discovered that all three of these are listed as carriers. Here is a copy:
Therefore, I do not think it can be offered for sale in the US. I'm sorry I can't be more encouraging. Perhaps your local nurseries could suggest a substitute.
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