I have seen just one real one and it was in a pretty poor state. Of course things survive in different condition but this one looks too good to be true and even from these low-res pictures it seems to lack the appearance of any great age. Does that leather band, or the fur, really look old? Can you really trust that plate, knowing that extremely accurate copies have been made?
Even after nearly four decades of collecting British kit from the Crimea to WW1, I may be totally wrong about this. If you "buy" the seller, fine, but it is perfectly possible to be an expert in one field and fooled in another, especially when you want something to be right. If it's real then of course it's a very fine piece, and if not it's an expensive mistake. Personally I have always have to feel very sure indeed about high-end purchases, but it's not my call here. I don't know the seller and I haven't handled the cap. All I can do is offer an honest, unbiased opinion based on what I see here.