Base Set Tangela #66: PSA 9 vs PSA 10
The PSA 10 to PSA 9 spread on Base Set Tangela #66 is a wide gem-mint premium: $73, with PSA 10 copies trading at 3.2x a PSA 9. Based on a recent PSA 10 sale of $107.52 on May 30, 2026, the math leans toward holding the 9: expected value turns negative at conservative upgrade probabilities once the resub fee is in.
PSA 10
$105.58
Last sale $107.52 on
PSA 9
$33.00
Last sale $37.51 on
PSA 8
$30.75
Last sale $29.50 on
The Spread
The PSA 9 to PSA 10 spread on Tangela #66 Base Set.
$73
Dollar gap, PSA 9 to PSA 10
3.2x
PSA 10 sells for 3.2x 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 #66 Tangela released in 1999 sits in the vintage WOTC tier where gem-mint premiums above $73 are common. PSA 10 populations shrink faster than supply on cards of this era, which is why the upgrade arbitrage stays alive.
More Tangela Comparisons
Other Base Set Heavy Hitters
Track every grade tier. Spot every gap.
Real PSA prices across every grade tier. Founding member rate $3.99/mo locked forever. First 100 only.
Claim founding member rateFirst 100 only. Founding member rate $3.99/mo locked forever.