Pure and simple: Only buy DIRECT FROM A VERIFIED MANUFACTURER.
Verified manufacturers:
Bitmain
Canaan (Avalons)
eBang (eBit miners)
Hotmine.
Bailkal/Panda(?)
I for one do not trust ANY reseller of mining gear as far too many are scams. If they are legit, then the pricing is always much higher than buying direct plus NO manufacturer uses distributors or resellers so that means no warranty.
Only reseller I'd trust is Giga Watt although they only sell miners to host. But you forgot to add INNOSILICON to manufacturers you can buy from, and I agree about avoiding resellers that only take crypto for payment, unless they take credit cards so you can get your money back it's a scam. Even if they take credit cards it's probably a scam but at least you can get your money back lol.