How to give a discount to the cheapest product in the cart?
If you’d like to set up a Buy 2, Get 1 Free promotion that would provide a 100% discount to the cheapest product in the cart when a customer adds 3 items, please create a cart price rule with the following configuration:
As soon as any 3 products are added to the cart, the promotion is going to select the cheapest one and apply the discount to it:
You can also narrow down the list of the products that are applicable to this promotion using the conditions tree under the 'Actions' tab. With the setup below, only each 3-rd product from Category 4 will be discounted: