I buy mine from a local grocery chain. This store is interesting to say the least when it comes to alcohol. Not only do they carry decent huadiao/ shaoxing. They also have $1000 bottle maotai right on the shelf by the entrance. And often times the staff isn’t present. I don’t know if they have the real bottles inside the box but the box sure felt heavy and I picked it up.
I am sure you will find some good ones at local grocery stores.