The Regirock ex (98 / 101) card can be found in the Hidden Legends set.
Recently sold 2 times and based on those sales is worth around £22.90.
Currently, there are 18 open listings for this card on ebay.
This card sells in the range of £21.38 to £24.42, making it very stable.
This Rare Holo Ex card was illustrated by Mitsuhiro Arita.
The fact that it is a EX card makes it one of the more valuable cards.