Current Battery Service fee for iPhone 14 series are US$99, for iPhone 13 and older full screen iPhone are US$69, for iPhone with home button are US$49.
Effective March 1, 2023, Battery Service fee for iPhone 13 and older model will get a US$20 increase, meaning they will be increased to US$89 and US$69 respectively.
Source: See the note under “Get an estimate” in the battery service page from Apple: https://support.apple.com/iphone/repair/battery-replacement
This price change will happen in other countries and regions at the same time as well. Open the link above and change the country/region at the bottom of the page to see the change for your country/region.