The Gardevoir (6 / 113) card can be found in the Delta Species set.
Recently sold 4 times and based on those sales is worth around £16.34.
Currently, there are 5 open listings for this card on ebay.
This card sells in the range of £7.13 to £25.55, making it quite stable.
This Rare Holo card was illustrated by Mitsuhiro Arita.