You can buy LG Airwasher KF94s from LG Household and Health Care on Amazon here

Dr. Puri also has an Amazon storefront (but only sell in 20 packs AKAIK) here

Some people often worry about Amazon's reported inventory commingling, in which buying from a legit seller is no guarantee to get a legit product, but I haven't heard of that actually happening to someone with KF94s. I don't think it happens with every type of product.