Can I buy a lost left Airpod?

You can get a new one by contacting the support: go to this page: AirPods Support - Official Apple Support

At the bottom click "Get support", then select the first option "setup" and click "Chat". Then explain to the operator that you have lost an AirPod; they will ask for your serial number (inside your charging case, it's small, on the inner top of the left side) and your details (for shipping and availability), send you a web payment link and you should be good to go.

Not quite as Apple says. I lost my airpods on the left side and when I contacted Apple's chat I was informed that I can not request as informed because I have to attend one of the company's stores to have my airpods inspected. SHOULD TREAT BETTER CUSTOMERS AND DO NOT GIVE WRONG INFORMATION ............. I LOST MORE THAN 04 HOURS CONVERSATING WITH 03 PEOPLE FROM THE APPLE. YOU CAN NOT PAY FOR THE LOST ITEM.

The same for me, I lost one, called to support and was told they can't sell me one, only full set.

A few minutes later support called back, apologized and told that I can buy one at the re-seller store 🙂