The Steelix ex (109 / 115) card can be found in the Unseen Forces set.
Recently sold 2 times and based on those sales is worth around £55.38.
Currently, there is 1 open listing for this card on ebay.
This card sells in the range of £20.76 to £90.00, making it highly 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.