The Tentacruel (66 / 110) card can be found in the Legendary Collection set.
Recently sold 4 times and based on those sales is worth around £34.72.
Currently, there are 4 open listings for this card on ebay.
This card sells in the range of £25.66 to £43.78, making it quite stable.
This Uncommon card was illustrated by Kagemaru Himeno.