63x63 card sleeves Vault X Standard Board Game 65.5 x 91mm (50 Pack) for Standard-Sized Cards and Trading Cards, Clear Premium Quality : Toys & Games That is 50% more than most Perfect Square Standard Sleeves (63.5x63.5mm)

This archetype made a giant splash in the TCG side of Yu-Gi-Oh

How about a supplemental set like Modern Horizons 3

By the looks of things (and judging by MTG Goldfish's price tracker) the Modern Masters 2017 version is the one that's gone up in value the most, from $11.80 at the start of June to $35 now

Kadabra [1st Edition] #32 (Pokemon Base Set | Pokemon Cards) prices are based on the historic sales

Orfeo, the Boulder Rakdos and Bant: Shagrat, Loot Bearer and Galea, Kindler of Hope Gruul and Esper: Meria, Scholar of Antiquity and Arna Kennerd, Skycaptain Selesnya and Grixis: Danitha, New Benalias Light and Tetsuo, Imperial Champion Orzhov and Temur: Ria Ivor, Bane of Bladehold and Pako, Arcane Retriever & Haldan, Avid Arcanist