The Regirock ex (99 / 106) card can be found in the Emerald set.
Recently sold 3 times and based on those sales is worth around £27.52.
Currently, there are 20 open listings for this card on ebay.
This card sells in the range of £22.62 to £32.42, making it stable.
This Rare Holo Ex card was illustrated by Hikaru Koike.
The fact that it is a EX card makes it one of the more valuable cards.