Having your own chooks for eggs, fish, fruit trees and vegetable garden helps a lot with avoiding most overly salted (and sugared) processed foods There is a disturbingly large amount of that stuff in the supermarket- several whole isles are pretty much no-go zones!
One thing to keep in mind is that the Sodium listed is only 40% of the weight of salt used. Atomic weight of Sodium = 23g, Chlorine =37g, the Sodium portion is a fraction under 40% of the total molecular weight. For example, you might expect that the 3450mg of Sodium per 100g of Vegemite= the amount of salt, but it is actually over 8.5% salt.
Regarding purchasing salt, as natural.thought says, it really makes no sense to buy it from half way around the world, when the same substance, just with reduced added marketing hype! is available from much closer to home.