The Miraidon ex (244 / 198) card can be found in the Scarlet and Violet set.
Recently sold 10 times and based on those sales is worth around £32.00.
Currently, there are 16 open listings for this card on ebay.
This card sells in the range of £24.61 to £39.39, making it quite stable.
This Special Illustration Rare card was illustrated by kantaro.
The fact that it is a EX card makes it one of the more valuable cards.