To be honest, when playtesting this deck, I generally was able to remove everything without needing to rely on Be Prepared
Sisay also scales with Magics ongoing obsession with legendary creatures, planeswalkers, legendary artifacts, and so on
A super enabler for decks that ramp obscenely then drop huge threats every turn
Michelangelo, Weirdness to 11 Who can't get behind a weird commander
More than anything, these moments seem to be self-perpetuating, where everyone gets tremendously excited about one particular card, which creates demand, which raises the price, which exaggerates the rarity, which creates demand The next most expensive right now is the Latias ex at almost $200, then the gold card version of the Pikachu ex at $100, and that Hydreigon pictured above at about $95