The Shining Mew (40 / 73) card can be found in the Shining Legends set.
Recently sold 7 times and based on those sales is worth around £35.00.
Currently, there are 28 open listings for this card on ebay.
This card sells in the range of £26.97 to £43.03, making it quite stable.
This Rare Shining card was illustrated by Sanosuke Sakuma.