Pretty much all of them are a scam. If you can, pay with a credit card. Then if you get nothing, file a section 75 with the card company and you’ll have your money back within a day.
If you can’t pay with any major debit/credit card, walk away.
What LNS said. Either way, as I am here I may as well do one arbitrary piece of moderation - we do not permit vendor discussion, whether they are legit or otherwise else we leave ourselves open to being accused of enabling people to score.