Strong Buy
Grading Gallade-EX #99 from Roaring Skies currently looks like a clear win. The gap between the $19.29 raw price and the $680.00 PSA 10 price gives a 522% Return on Grading. The upside only holds if the copy grades a 10, so inspect edges and surface first.
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)
Pays off even at PSA 9
A PSA 9 alone ($120.00) already covers your $109.29 cost (raw + grading + shipping), so you don't need the 10 to come out ahead.
Anything from a 9 upwards puts you ahead, and a 10 would net you $570.71. The only real risk left is the card grading below a 9.
Among the 43 cards in Roaring Skies with PSA 10 sale data, Gallade-EX ranks 22nd for Return on Grading and 23rd by PSA 10 price. Of the 10 Rare Ultra cards with PSA 10 sales, it is 8th for Return on Grading. The median PSA 10 in this set sells for $749.99. 28 of the 43 clear a 100% Return on Grading.