The Mantyke (55 / 130) card can be found in the Diamond and Pearl set.
Recently sold 4 times and based on those sales is worth around £9.61.
Currently, there are 2 open listings for this card on ebay.
This card sells in the range of £3.70 to £15.52, making it quite stable.
This Uncommon card was illustrated by Midori Harada.