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Sending the Rare Rainbow Brandon from Silver Tempest to PSA would most likely lose money today. A 1% Return on Grading comes from the spread between $4.94 raw and $96.00 graded. Grading and shipping fees would eat whatever margin is there.
Most grading maths asks you to guess your odds of a PSA 10 first. This works backwards from the prices instead and tells you what those odds would have to be.
The number is different on every card. It's how confident you'd need to be that this copy gems before grading pays for itself, so 20% means roughly a 1 in 5 shot and 50% means a coin flip.
Grade it if you rate your copy better than that, leave it raw if you don't.
It assumes a 9 is the worst you'll get. Centering and edge whitening send plenty of modern cards back at 8 or lower, and that's not priced in here, so treat this as the floor of the bar rather than the whole of it. Selling fees aren't counted either.
(cost - PSA 9) ÷ (PSA 10 - PSA 9)
You need at least
a copy you'd bet on gemming almost every time for this to pay off.
You'd be risking $74.44 to make $1.06, so the 10 has to be close to certain before this is worth doing.
Among the 83 cards in Silver Tempest with PSA 10 sale data, Brandon ranks 15th for Return on Grading and 17th by PSA 10 price. Of the 13 Rare Rainbow cards with PSA 10 sales, it is 2nd for Return on Grading. The median PSA 10 in this set sells for $46.25. 3 of the 83 clear a 100% Return on Grading.