The Groudon (102 / 101) card can be found in the Hidden Legends set.
Recently sold 6 times and based on those sales is worth around £20.00.
Currently, there are 3 open listings for this card on ebay.
This card sells in the range of £8.11 to £31.89, making it quite volatile.
This Rare Secret card was illustrated by Mitsuhiro Arita.