The Umbreon (24 / 100) card can be found in the Sandstorm set.
Recently sold 3 times and based on those sales is worth around £17.65.
Currently, there are 8 open listings for this card on ebay.
This card sells in the range of £12.50 to £22.80, making it quite stable.
This Rare card was illustrated by Kagemaru Himeno.