Brock's Sandslash #23 from Gym Heroes is a rare card that currently sells for about $8.99 ungraded, with graded copies ranging from $14.00 at grade 7 to $37.09 at grade 10. A grade 10 copy sells for around $37.09, about 4.1× the $8.99 raw price, so high-grade copies are worth grading.