The Gyarados (8 / 110) card can be found in the Holon Phantoms set.
Recently sold 11 times and based on those sales is worth around £23.23.
Currently, there are 12 open listings for this card on ebay.
This card sells in the range of £6.27 to £40.19, making it quite volatile.
This Rare Holo card was illustrated by Hajime Kusajima.