Know of nothing shipped…because the weight kills you.
In the NJ/PA area, we have a couple LFS’s that have salt at close to cost (or maybe I should just say the cheapest I’ve seen it). They figure they’ll get you on other stuff.
I buy my IO salt from petco, 50 bucks a bucket is by far the cheapest around here. I do live in Alaska so its probably cheaper down in the lower 48 becuase of shipping.