As this is my first post, first of all a hello to everyone.
Having only ever read here and benefited from the experts here, I can offer a possible explanation for this phenomenon.
As darlym has already written, this is due to the demand, or more precisely the demand for the HP MAX in Germany.
To cut a long story short, Jörg Sprave (YT Slingshot Channel) launched an F version (i.e. below 5.5 ftlb muzzle energy) of the HP MAX cal .35 1.5 years ago, which anyone over the age of 18 can easily purchase. He also includes all the parts you need to bring the rifle to full power, because you can legally own them, just not install them yourself.
And the result?
If you believe his statements on YT, he has sold around 25,000 units in 1.5 years at a price of €1,099.
His target group is not the average shooter but the prepper scene who are preparing for the end of the world. Since firearms are not easy to buy and own legally in Germany and only with considerable effort, and there are no other large-caliber air rifles that you can simply buy (and also bring to full power for self-defense without much effort), the HP MAX is still "the next big thing" in Germany, and people are simply paying the price.
Even if Jörg Sprave sometimes comes across as slightly crazy in his videos (some of which are also available in English, by the way), he is a damn good businessman and understands marketing. Firstly, he was the first one who throttled large-caliber air rifles to such an extent that he can legally sell them to anyone over the age of 18 in Germany (which, by the way, must be checked and certified by the German authorities, which is not exactly cheap) and secondly, he addresses his target group precisely in his videos by repeatedly talking about the collapse of the state and the legal system or the zombie apocalypse.
And if the Germans can sell thousands of 5.5ftlb HP MAX for €1,099, why shouldn't the Spaniards (who have a 24 joule limit) be able to charge €900 for them?
Hope that explains it.