The Squirtle (64 / 100) card can be found in the Crystal Guardians set.
Recently sold 4 times and based on those sales is worth around £21.64.
Currently, there are 6 open listings for this card on ebay.
This card sells in the range of £16.17 to £27.11, making it quite stable.
This Common card was illustrated by Hajime Kusajima.