I just ordered Mganesium oil from the site below. I looked around. It seems to have the best reputation. While I was there I picked up a bottle of their Iodine too. I have Lugol's, just thought I'd check it out.
Their are 2 versions of the Magnesium chloride--one is called "Ocean" the other is "ancient". The Ancient was a little more expensive but has a guaranteed purity and composition anaysis.