Base Set Gastly 50/102: PSA 9 vs PSA 10
On Base Set Gastly 50/102, PSA 10 sells for 4.4x a PSA 9, a $132 delta, which is a wide gem-mint premium. Based on the last tracked PSA 10 sale of $136.50 on May 11, 2026, the math leans toward holding the 9: expected value turns negative at conservative upgrade probabilities once the resub fee is in.
PSA 10
$170.47
Last sale $136.50 on
PSA 9
$38.81
Last sale $31.00 on
PSA 8
$23.90
Last sale $21.21 on
The Spread
The PSA 9 to PSA 10 spread on Gastly 50/102 (Base Set).
$132
Dollar gap, PSA 9 to PSA 10
4.4x
PSA 10 sells for 4.4x 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
Base Set 50/102 Gastly is a WOTC-era release from 1999. The gap between its PSA 9 and PSA 10 prices is $132.
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