Just use coupon code CYBER30
at checkout. Available on ALL products with the exception of Mint Chocolate and bundles.
Similar price to their buy 2 get 1 free, but the $5 giftcard might put it over for a small order, and it looks like it will stack with the 5% discount for subscribe and save orders, though the 30% bonus is just for the first order, so cancel after delivery. It's not clear if you get the $5 gift card per transaction, or per account using the code, so YMMV on that for multiple transactions.
The fine print from the email that promoted this:
*Offer expires 11:59 PM PST on 12/02/19 while supplies last. A free $5 digital gift card will be emailed to your account email address by December 31, 2019. Sale does not apply to Mint Chocolate or Bundles. Valid on one-time purchases and first subscription orders. Discount does not apply to previous orders and cannot be combined with other offers. US residents only.