The Dark Steelix (10 / 109) card can be found in the Team Rocket Returns set.
Recently sold 5 times and based on those sales is worth around £12.08.
Currently, there are 4 open listings for this card on ebay.
This card sells in the range of £2.81 to £21.35, making it quite stable.
This Rare Holo card was illustrated by Kyoko Koizumi.