The 1-bottle package carries a 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 1-bottle package is $79/bottle for a 30-day supply, totaling $79, plus a separate shipping charge — while the 3-bottle and 6-bottle packages both include free US shipping.
Since this formula's own materials describe probiotic effects typically taking 4 to 8 weeks to become noticeable, a 30-day supply on the smallest package barely covers the earliest phase — worth weighing that timeline alongside the free-shipping value of the larger packages.