Koraidon ex #29 from Scarlet & Violet Black Star Promos is a reverse holo promo card that currently sells for about $0.81 ungraded, with graded copies ranging from $5.00 at grade 7 to $21.26 at grade 10. A grade 10 copy sells for around $21.26, about 26× the $0.81 raw price, so high-grade copies are worth grading.