How can I buy a replacement airpod I lost

Refer to: AirPods Repair & Service - Apple Support

- Includes replacement cost. Note the distinction between lost and damaged items. Neither the warranty nor AppleCare+ helps with the cost of Airpods that are lost or stolen. The cost for damaged Airpods may be lessened by any 'AppleCare+ For Headphones' coverage you may have.

Unfortunately, Apple does not sell individual AirPods on the shop, however, you can contact Apple support for a replacement.

Here is a link: AirPods Repair & Service - Apple Support