The Vaporeon V (SWSH181) card can be found in the Swsh Black Star Promos set.
Recently sold 15 times and based on those sales is worth around £24.00.
Currently, there are 23 open listings for this card on ebay.
This card sells in the range of £18.04 to £29.96, making it quite stable.
This Promo card was illustrated by Tika Matsuno.
The fact that it is a V card makes it one of the more valuable cards.