Tropical Tidal Wave #HGSS18 from HGSS Black Star Promos is a holo promo card that currently sells for about $650 ungraded, with graded copies ranging from $1,154 at grade 9 to $1,400 at grade 10. A grade 10 copy sells for around $1,400, about 2.2× the $650 raw price, so high-grade copies are worth grading.