They don't hold their value but by the same token there are fakes out there. Maybe get it authenticated before purchasing. You can usually tell from the tags if they are authentic or not.
Thanks for your reply, yes that was my other thought whether they just didn't hold their value very well hence the low price. Do you mean you can usually tell from the sewn in labels in the jacket? If so do you know if there is anything in particular to look out for. I think if I bought it I would be able to tell if it was authentic or not from the quality etc but one of the biggest red flags for me is that the jacket is from the fall/winter 19/20 collection and the seller is selling it with the most recent holiday packaging (bag and box). Could just be that they had a spare box or something I don't know...