SWSH07: Evolving Skies Boost Shake #229: PSA 9 vs PSA 10

SWSH07: Evolving Skies Boost Shake #229 shows one of the widest gaps in vintage WOTC between PSA 9 and PSA 10: a $36 dollar gap, with the gem mint multiplier at 9.4x. Based on a recent PSA 10 sale of $49.99 on May 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

$40.00

Last sale $49.99 on May 28, 2026 UTC

PSA 9

$4.25

Last sale $4.25 on Feb 23, 2026 UTC

PSA 8

$9.51

Last sale $9.99 on Oct 17, 2023 UTC

The Spread

The PSA 9 to PSA 10 spread on Boost Shake #229 SWSH07: Evolving Skies.

$36

Dollar gap, PSA 9 to PSA 10

9.4x

PSA 10 sells for 9.4x 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

Where this card lands in the broader SWSH07: Evolving Skies picture: a non-holo with a $36 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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