For iPhone in the US battery replacement is not expensive. A battery replacement not covered by the warranty or Apple Care ranges from $70 for really old phone

For iPhone in the US battery replacement is not expensive. A battery replacement not covered by the warranty or Apple Care ranges from $70 for really old phones to $100-120 for the latest models (the high end is a range because it depends on whether you have the regular model or a pro or max). That’s way cheaper than a new iPhone. It’s even cheaper if you use a third party repair place instead of Apple. Third party repair places are common even in small towns. In my small town there is one inside the Walmart and one in a standalone shop, and in the small town around 8 miles away there are two in the mall and one or two standalone ones.