The Garchomp & Giratina GX (247 / 236) card can be found in the Unified Minds set.
Recently sold 4 times and based on those sales is worth around £27.32.
Currently, there are 2 open listings for this card on ebay.
This card sells in the range of £19.37 to £35.27, making it quite stable.
This Rare Rainbow card was illustrated by aky CG Works.
The fact that it is a GX card makes it one of the more valuable cards.