my reply was simply, dont worry about the difference because they all work fine, each with their pro and con. You said what is the most reasonable price, they are all priced around the same place, and from where is your lfs. Simply put, just get whatever you can put your hands on.
im not sure about the kilo things and pounds, but here in america, i get a 5 gallon bucket full of salt (says 20.3 kilos) for about 48 dollars. Its reef crystals.
If the salt is too expensive, look for another store that sells cheaper salt. As long as its marine salt you should be fine.