Anyone know where to get bulk sea salt?

[dissimilus]

I'm looking for cheap industrial grade, not fancy "food safe" sea salt. Needing about a gallon or so for metalurgy pursuits and don't want to buy a gazillion little containers at QFC.

Just for funzies I may eventually see just how much I can get from evaporating a gallon of water from the sound, but for now I'm lazy.