The Rayquaza GX (177A / 168) card can be found in the Celestial Storm set.
Recently sold 10 times and based on those sales is worth around £35.00.
Currently, there are 7 open listings for this card on ebay.
This card sells in the range of £29.60 to £40.40, making it quite stable.
This Rare Ultra card was illustrated by 5ban Graphics.
The fact that it is a GX card makes it one of the more valuable cards.