The Umbreon (24 / 100) card can be found in the Sandstorm set.
Recently sold 4 times and based on those sales is worth around £24.06.
Currently, there are 2 open listings for this card on ebay.
This card sells in the range of £14.43 to £33.69, making it quite stable.
This Rare card was illustrated by Kagemaru Himeno.