You're making the significant assumption that the original part is either still available, or was ever available for individual sale (often, batteries that aren

You're making the significant assumption that the original part is either still available, or was ever available for individual sale (often, batteries that aren't considered user-replaceable are never sold directly.) Apple systems are generally better off in this regard as vendors like iFixit can make official batteries available for older systems, but for other vendors, no such luck. For example: I can't find any source for an official Lenovo battery for my first-gen X1 Carbon. It's also long since out of warranty. There is still the time consideration, but assuming you have time available to do the work, why not?