Er indoors had been buying it at Siam Drug in Airport Plaza but appears to have very recently closed down.

Has it been seen in the wild elsewhere?

Thanks

Good luck. In the past I tried everywhere in Chiang Mai (except Siam Drug); have read elsewhere one or two places in Bangkok might stock it. I now bring it with me when I come to Thailand.

Been trying for years, without success. I also bring it with me.