Voltorb #100 from 151 is a common card that currently sells for about $8,500 ungraded, with graded copies ranging from $11,737 at grade 9 to $12,911 at grade 9.5. A grade 9.5 copy sells for around $12,911 vs $8,500 raw. That's a modest premium, so grading only pays off for near-perfect copies.