Amazon gives non-Prime members free shipping at $35 or more of eligible items. Instead of simply letting users get the product with free shipping, they’ve added a discount that prices it exactly one cent below the $35 limit, while only subsidizing the price with $3.38, which is about half of what they’ll then charge you for shipping.
I usually just… go to the store.
I always try to buy in the store, but most of the time the store either doesn’t have the item I need or it costs 200%.