The Altaria ex (90 / 106) card can be found in the Emerald set.
Recently sold 4 times and based on those sales is worth around £30.09.
Currently, there are 6 open listings for this card on ebay.
This card sells in the range of £19.11 to £41.07, making it quite volatile.
This Rare Holo Ex card was illustrated by Ryo Ueda.
The fact that it is a EX card makes it one of the more valuable cards.