I feel like the price Apple charges for batteries is very reasonable. I kept my phone going for 4.5 years thanks to a battery replacement 2 years in. They’re basically doing it at cost, considering parts and labour.

Also, your information is slightly out of date. It’s possible to do the replacement yourself if you want. Here’s an ifixit guide based on apples official repair guide - https://www.ifixit.com/Guide/iPhone+17+Battery+Replacement/1...

It is so, so long... I barely reached the middle before my brain just "Nope."

They are talking about this kind of battery replacement: https://www.ifixit.com/Guide/Fairphone+3+Battery+Replacement... . The "TV remote" battery replacement kind.