The Flying Pikachu (25 / 53) card can be found in the Wizards Black Star Promos set.
Recently sold 14 times and based on those sales is worth around £23.00.
Currently, there are 4 open listings for this card on ebay.
This card sells in the range of £15.67 to £30.33, making it quite stable.
This Promo card was illustrated by Toshinao Aoki.