Base Set Grass Energy #99: PSA 9 vs PSA 10
The PSA 10 to PSA 9 spread on Base Set Grass Energy #99 is a meaningful PSA 10 premium: $50, with PSA 10 copies trading at 2.1x a PSA 9. Based on the most recent PSA 10 sale of $95.00 on Apr 28, 2026, the math leans toward holding the 9: expected value turns negative at conservative upgrade probabilities once the resub fee is in.
PSA 10
$95.00
Last sale $95.00 on
PSA 9
$44.99
Last sale $44.99 on
PSA 8
$15.17
Last sale $14.00 on
The Spread
The PSA 9 to PSA 10 spread on Grass Energy #99 Base Set.
$50
Dollar gap, PSA 9 to PSA 10
2.1x
PSA 10 sells for 2.1x a PSA 9
Three-Outcome EV Calculator
15%
70%
15%
Defaults are conservative starting points. Adjust based on the specific slab. A borderline 9 with strong centering plays differently than a 9 with edge wear.
PSA 10 outcome (sale price minus resub minus acquisition)
$0
PSA 9 outcome (regrade, no upgrade)
$0
PSA 8 outcome (downgrade, slower sell, tied capital)
$0
Expected Value
$0
Math favors holding the 9
Where this card lands in the broader Base Set picture: a non-holo with a $50 gap between PSA 9 and PSA 10. The PSA 9 to PSA 10 jump on WOTC-era cards reflects population scarcity at the top grade, not raw print run.
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