Strong Buy
the Rare Holo EX M Gengar-EX from Phantom Forces ranks among the best cards to send to PSA right now. At $152.19 raw against $10400.00 for a PSA 10, that works out to 4194% ROG. Centering is usually the limiting factor on cards like this — check it carefully before sending.
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 ($357.69) already covers your $242.19 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 $10157.81. The only real risk left is the card grading below a 9.
Among the 30 cards in Phantom Forces with PSA 10 sale data, M Gengar-EX ranks 2nd for Return on Grading and 3rd by PSA 10 price. Of the 8 Rare Holo EX cards with PSA 10 sales, it is 1st for Return on Grading. The median PSA 10 in this set sells for $311.68. 19 of the 30 clear a 100% Return on Grading.