I understand if you prefer cards in your language, I only have English versions in my cubes, but these are just breathtaking: Swords to Plowshares (current price for JP alt art in traditional foil: $30) There are a few versions of this card that are more than $30, but those are judge promos or Unlimited and older
While some of those answers were clever, many of them were blatant sledgehammers designed to blow out the mechanic
However, if you want a shot at the Van Gogh Pikachu promo card you may still be able to score one from Pokmon Center
Rare cards listed for suspiciously low prices are almost always fake
This, again, does require more set up than a few of the other ways to end the game
As for Teferi, Time Raveler, I really tried to play the deck without Teferi, but after getting Ultimatums repeatedly countered by Mystical Dispute and Dovin's Veto, I decided that actually being able to resolve our Ultimatums made it worth being a dirty Teferi player, although we only have two copies in the main deck