All good points. It is a machine worth over 500. You do bring up a good point, some sellers might not even have the need to purchase a new battery since this one does function for some amount of time (~1hr on a 9cell).
If I replace the battery I wouldn’t do third party since they will be flagged by the computer as non-genuine, but if the new owner doesn’t mind then I guess I can leave them to make that decision.