The Butterfree (21 / 110) card can be found in the Legendary Collection set.
Recently sold 12 times and based on those sales is worth around £39.84.
Currently, there are 4 open listings for this card on ebay.
This card sells in the range of £23.65 to £56.03, making it quite volatile.
This Rare card was illustrated by Kagemaru Himeno.