The Mew (8 / 53) card can be found in the Wizards Black Star Promos set.
Recently sold 11 times and based on those sales is worth around £3.99.
Currently, there are 66 open listings for this card on ebay.
This card sells in the range of £2.27 to £5.71, making it very stable.
This Promo card was illustrated by Ken Sugimori.