This depends on the country and quality; generally an extremely low cost.
about 2 dollars
$3.50 at a supermarket
1Kg of salt costs Rs11 in India
2.99 on average
$3.48
12cents
it cost, half million dollars...
less than $1
a billion pounds
A lb. box of salt cost about 10-12 cents in 1980.
Salt is not a magnetic compound; the magnetic susceptibility is very low.