Update: According to MrConway on the forums, you have to log in on the premium shop’s site to be able to view the offer and everyone can buy it.
Get the OP monster for 6 Euro! (lol) No bundle 🙂 Joking. Looks like only selected players (me included) can buy it.
This is a personal offer, only a selected few people can buy it, or players who haven’t got it when it was in the advent calendar.
https://eu.wargaming.net/shop/wot/main/3067/