Where to buy?

You are welcome.

I was also a little confused seeing, in the prices section, "AirPods (3rd generation)" and "AirPods" but nothing about the 2nd generation. To make sure you get correct information you should speak to Apple Support directly.

"Contact Apple Support.

You can also discuss your service options with an Apple Support advisor by phone. You'll need your serial number. For AirPods or AirPods Pro, you can find it on your Charging Case on the underside of the lid. 

Learn more about your AirPods  

How to find your AirPods serial number 

Get ready for service

Get service"

Hello,

This article has the information about purchasing replacement AirPods.

AirPods and AirPods Case Replacement - Official Apple Support

I hope this helps.