The Zygarde GX (73 / 131) card can be found in the Forbidden Light set.
Recently sold 3 times and based on those sales is worth around £4.63.
Currently, there are 6 open listings for this card on ebay.
This card sells in the range of £2.46 to £6.80, making it very stable.
This Rare Holo GX card was illustrated by 5ban Graphics.
The fact that it is a GX card makes it one of the more valuable cards.