Like most One Piece TCG cards, the value of Sengoku depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Starter Deck 33: BLUE Kuzan)
[Update 28 Aug 2024] As per information posted on PokBeach, the Grand Adventure Collection will not be released in Europe
All three versions are getting cheaper as time passes, and as this set stays in print, the nonfoils, the traditional foils, and the surge foils are all going to trickle downwards in price
3 Raikou: Skyridge (Holo Rare) $249.50 One Of The GOATs The most valuable cards from Skyridge feature several of the most expensive cards of all time, though this Raikou rarely sells on TCGplayer, boasting only a small handful of sales that set the current market price