Worth paying Apple the money
Everything the poster above me said is true, plus you get a genuine battery, so no warnings on your device and also the mAh will be accurate and your battery won't swell, catch fire or anything catastrophic. Not to mention, your battery health won’t plummet like they do with aftermarket batteries
I will say though, at 78% with an iPhone X, I would be looking at the used market for a newer iPhone like the 12 Pro Max and beyond at least.