SWSH12: Silver Tempest Unown VSTAR #66: PSA 9 vs PSA 10

The PSA 10 to PSA 9 spread on SWSH12: Silver Tempest Unown VSTAR #66 is a wide gem-mint premium: $31, with PSA 10 copies trading at 3.9x a PSA 9. Based on a recent PSA 10 sale of $47.79 on May 29, 2026, the math leans toward holding the 9: expected value turns negative at conservative upgrade probabilities once the resub fee is in.

SWSH12: Silver Tempest Unown VSTAR #66 Holo

PSA 10

$41.16

Last sale $47.79 on May 29, 2026 UTC

PSA 9

$10.50

Last sale $10.50 on May 24, 2026 UTC

PSA 8

$12.50

Last sale $12.50 on Dec 15, 2025 UTC

The Spread

The PSA 9 to PSA 10 spread on Unown VSTAR #66 SWSH12: Silver Tempest.

$31

Dollar gap, PSA 9 to PSA 10

3.9x

PSA 10 sells for 3.9x a PSA 9

Three-Outcome EV Calculator

PSA 9 acquisition cost ($)

PSA resub cost ($)

Probability of each outcome (must total 100%)

PSA 10 (upgrade) 15%

PSA 9 (regrade) 70%

PSA 8 (downgrade) 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

Math favors holding the 9

SWSH12: Silver Tempest #66 Unown VSTAR Holo released in 2022 sits in the vintage WOTC tier where gem-mint premiums above $31 are common. PSA 10 populations shrink faster than supply on cards of this era, which is why the upgrade arbitrage stays alive.

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