Maybe they were of the same creature type, or showed a similar creative element, or just played well together
Flashback Some spells are so fun you simply must cast them again, and flashback allows you to do just that
This sudden price shift was likely the result of market manipulation, in which a group of individuals buys every copy of a card, then sells it at a higher, set price
Abyssal Harvester Arbiter of Woe Bloodletter of Aclazotz Bone-Cairn Butcher Bringer of the Last Gift Chaos, the Endless Demon Wall Desecration Demon Doomsday Excruciator Fiendish Panda Gurmag Rakshasa Ifrit, Warden of Inferno Iron Giant Madame Null, Power Broker Miasma Demon Perforating Artist Rakdos, Patron of Chaos Rakdos, the Muscle Reckless Detective Rot-Curse Rakshasa Rune-Scarred Demon Savanti Romero, Time's Exile Shefet Archfiend Sower of Chaos Summon: G.F
Then why dont they just take cards that are at risk for being too good and make them Dragons
People in the various misprint communities have already come to rely heavily on CGCs grading and their self touted expertise