Greninja #XY24 from XY Black Star Promos is a reverse holo promo card that currently sells for about $19.99 ungraded, with graded copies ranging from $29.46 at grade 7 to $19.00 at grade 10. A grade 10 copy sells for around $19.00 vs $19.99 raw. That's a modest premium, so grading only pays off for near-perfect copies.