The Professor Elm's Lecture (213 / 214) card can be found in the Lost Thunder set.
Recently sold 18 times and based on those sales is worth around £26.04.
Currently, there are 4 open listings for this card on ebay.
This card sells in the range of £18.30 to £33.78, making it quite stable.
This Rare Ultra card was illustrated by Hideki Ishikawa.