I live in Costa Rica, SN is my plan B and just waiting for my old dog to die first. Tried finding it around here but all I found were industrial suppliers of e.g. entire containers or "sacos" which obviously are not too practical (plus I suspect you have to work
in a business in a relevant industry to purchase).
Finally got some earlier this year from DMC. I had low hopes and it took a couple of weeks but eventually I got it through Correos and I didn't even have to pay any aduanas fee or anything! It came in a little black-wrapped box, and the powder is really tightly packed and looks almost like a little brick, so I guess it doesn't catch anyone's attention. Incredible given we can't even buy vitamins from amazon so easily
Can't post DMC link, but all I can say is that digging around this site I found enough clues and it was pretty obvious when I eventually found it.
PS - the payment methods listed in the site are not available here, don't even bother installing apps etc... There is an option called something like "unconventional payment method", when you get the email confirming your order ask for that one and follow instructions.
Good luck!