3rd Generation Airpod Case Replacement

I lost my 3rd gen Airpod case last week and have been searching for a replacement, but I cannot find any on the Apple website. only used on 3rd party websites. When I go to the replacement website, it only lets me purchase a new Airpod, not a new case. Would I be able to go into an Apple store to buy a replacement? Or is there somewhere I can buy a new one online that I haven't been able to find?