If we just focus on the Mythic Extended Art vs Regular Art versions we see a multiplier of a little under 2, however, I think it's fair to argue that since the Extended Art variants are only available from Collector Booster packs and Collector Booster packs are a limited print run we will likely see this multiplier climb as the initial first wave of cards from the Collector Boosters dries up
Excadrill #1406 Pokemon Chinese Gem Pack 4 Keep track of your collection value over time
This page shows current market prices, recent eBay sales, PSA graded values, and price history for this Rare Secret card from Phantom Forces
The other page is a maze activity also featuring Pikachu
WotC again went with a cat for a built-in Curiosity-like effect
The last two of these were specifically meant to clarify Shadow's relationship as Relm's father, with a cut follow up scene where Strago would have confronted him alone to confirm his identity