Where can I get a battery replacement for an iPhone 8?

What Best Buy told you is incorrect. Apple, at least in the US, will still replace batteries in iPhones back to the iPhone 6s unless their estimator is out of date. See:

iPhone Battery Replacement - Apple Support

What Best Buy will or will not do is up to them, though in my experience they often duck the issue on things they just prefer not to handle.

Regards.

Those devices are considered vintage. Apple may or may not have parts available for them anymore. It will depend on stock at your local store.

As noted above. You can have it done by a 3rd party, but the batteries will not be genuine new Apple parts and you risk losing touch or Face ID permanently.

There are independent shops who will replace the battery in your obsolete phone, but they won’t be Apple batteries and the battery condition monitoring feature would work.

Why do you risk losibg touch & face id? Would someome still be able to get phone unlocked? Im not the original poster, but have a iphone 8+ ,& battery is really bad & needing to get replaced.

Because many unauthorized shops don't know what they're doing (or don't care) or are often unusing unapproved, stolen, or faulty or incompatible parts, any of which can cause damage or result in faulty operation or even complete failure. It's almost always best to use authorized Apple service centers. Not that they can't make mistakes, but at least you can be reasonably certain that they're using proper Apple-approved parts and have had at least the minimum of training.

Regards.

raffertybr wrote:

Hi Varjak Paw, Thank you for your response! The Apple site comes up with repair places that are nearby Apple Stores & Best Buy stores with Apple service people that are authorized Apple repair shops. Best Buy gave me that information, but I'm going to contact the local Apple shops as you may be correct; I'd rather have Apple install it anyway as there may be a warranty.

Apple repairs come with a 90 day warranty.