The 2-bottle package carries a standard shipping charge that the 3- and 6-bottle packages don't — worth doing the actual math before assuming it's the cheapest way to test the formula.
The 2-bottle package is $79/bottle for a 60-day supply, totaling $158, plus standard shipping — while the 3-bottle and 6-bottle packages both include free US shipping and bonus guides.
Since this formula's own materials describe an initial adjustment period before a fair evaluation, worth weighing the smaller package's added shipping cost and missing bonuses against the larger packages' full value.