Rainbow refraction is crisp and evenly distributed across the illustration
Like most Pokmon cards, the value of Gengar-EX depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Phantom Forces)
These are put in so we can provide as much value as possible within the framing of the list
151 is likely coming to the end of its run, so prices will only go up unless the interest from the investing community fades
(Like in my PC box - I still haven't caught Uxie in my Alpha Sapphire to trigger its encounter.) Take note that your Pokemon typings might create some weird interpretations as additional monster Types where Plate Counters are concerned, unless there's a reason for using Pokemon as a subtype, like Spirit, Flip, or Tuner
The only way to get the promotional card was to attend the convention, so it was the perfect opportunity for resellers to take advantage of players who had missed out