These firms get it from abroad, India, Spain etc. Apart from the paying process which can be dodgy,I would be wondering if I were receiving the real thing. I know many on here do this and are satisfied with what they get, but I am wary.
Subscriptions to Dermatica and Skin and Me seem expensive but at least they’re legitimate. You have to go through a consultation process and once approved, every three months they will checkup on you and you have to submit photos and answer questions.