Retailer: … B071XXXK2X

Just missed their ATL of $17.81 supposedly.

Looks like an official Nintendo product. Looks interesting. Personally I’ve left my Joy-Con not attached to my switch, and had them dead before. And since I don’t play a lot, it was annoying.

Using AA batteries, the Joy-Con™ (L)/(R) AA Battery Pack accessory extends the battery life of Joy-Con controllers. Great to have when you want to play for a longer time without charging. Includes a Left and Right Joy-Con AA Battery Pack and 4 AA batteries. Controllers sold separately.

Amazon product: Nintendo Switch Joy-Con (L/R) AA Battery Pack
Customer Reviews:
perfect to give more size to those tiny controllers which i hate (too small for me and my 13 year old kid) and also great when you dont have other controllers and dont want to wait it to charge to play on your big screen. just replace the batteries and you are ok to go with this.