From personal experience

Kaboomracks and minefarmbuy are legit sellers

The one mentioned above, lychee, I messaged and ask him "how do I know he is legit". His response was he has done many good deals.

Which is no proof. Then in his next post in his own channel he posted video of hundreds of s19s with his name written on a piece of paper.

I'm intrigued to say the least. But I refuse to jump first.

As for now, if I want another computer I'll use sellers I trust.