Andreas that is absolutely not a “stunning” Kürassier helmet. When you are looking to buy a helmet of any kind, In addition to being correct, there are three things you need to have:
1. Condition
2. Condition
3. Condition
If you buy junk you own junk. Original Pickelhauben, even issued examples, are very well made, and very high quality.
So may I recommend this: as Bruno rightfully suggested, search and look at every example you can find here on this forum. However, to help you quickly, compare every image on that eBay sale to a good example, and let’s use mine.
https://www.kaisersbunker.com/dunkelblau/helmets/dbh25.htm
Compare every shot. You will see that the eBay helmet you are considering no serious collector would consider. It’s so bad, I had to take “Stunning” out of your title because that one is not. It’s awful. Where are the eagles eyes? Like an Alien. The parade eagle is not even close to the quality of an original. The Wappen is not correct as mentioned. Why is the helmet shell so small that the Kokarden are hanging down on the bottom? Do you really think a soldier would wear it like that? Why is there aged black leather on the rear tail? Personally I don’t like anything about that helmet.
This is what a quality looks like. This example below was brought back to the US by an American vet. And you can find one. They are not rare, just expensive. Be patient. Be selective, and as has been mentioned, be informed.