The Porygon-Z (100 / 100) card can be found in the Majestic Dawn set.
Recently sold 4 times and based on those sales is worth around £19.20.
Currently, there are 8 open listings for this card on ebay.
This card sells in the range of £3.81 to £34.59, making it quite volatile.
This Rare Holo Lv X card was illustrated by Ryo Ueda.