Add the sample box to your cart and use promotion code GOODSTART at checkout. I tried using this code from a non-Amazon Mom account and it did not work, but some folks in the Slickdeals thread reported success.
While I personally used this formula for my baby, she is now on whole milk (thank g’d as formula is so damn expensive!) so I no longer have a need. I personally am going to order it though and either give it to another mom in need or donate to a food bank.