Amazon sells it in a 42 oz. container for $38. Just search Saltwash...Hope this answers your question.
Have you thought of trying Amazon if you can't find it locally?
You can order it at Amazon.com
You can also make your own with table salt. I have a DIY here if you'd like to check it out... http://beautyforasheshome.com/using-salt-wash-to-create-a-chippy-look/