The Sylveon V (184 / 203) card can be found in the Evolving Skies set.
Recently sold 18 times and based on those sales is worth around £58.00.
Currently, there are 46 open listings for this card on ebay.
This card sells in the range of £49.47 to £66.53, making it quite stable.
This is a Rare Ultra card.
The fact that it is a V card makes it one of the more valuable cards.