Hardware store, home improvement center, restaurant / janitorial supply, nursery or garden center. Or on line if you are an internet shopper.
Amazon. Walmart online--order it and then pick it up at the store.
I buy it at Lowe's or Home Depot. By me it's sold as cleaning vinegar.
I’m not sure if it would be the same but regular white vinegar can also be diluted with water... I hope this helps!