Mawile-EX #XY103 from XY Black Star Promos is a reverse holo promo card that currently sells for about $5.44 ungraded, with graded copies ranging from $32.33 at grade 7 to $168 at grade 10. A grade 10 copy sells for around $168, about 31× the $5.44 raw price, so high-grade copies are worth grading.