Mewtwo #XY101 from XY Black Star Promos is a reverse holo promo card that currently sells for about $14.54 ungraded, with graded copies ranging from $26.30 at grade 7 to $999 at grade 10. A grade 10 copy sells for around $999, about 69× the $14.54 raw price, so high-grade copies are worth grading.