The Gengar (10 / 144) card can be found in the Skyridge set.
Recently sold 1 times and based on those sales is worth around £43.50.
Currently, there are 6 open listings for this card on ebay.
This card sells in the range of £43.50 to £43.50, making it very stable.
This Rare card was illustrated by Kyoko Umemoto.