How much to replace a iPhone 6 battery and how long does it take?

For the 'iPhone Service Answer Center' click here --> https://support.apple.com/iPhone/repair/service

For instructions on how to 'Get your iPhone, iPad, or iPod touch ready for service' click here --> https://support.apple.com/HT201557

- "To protect your information and save time, follow these steps before you get service for your device."