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.
You used to be able to buy digital Amazon gift cards for a dollar. You would use the credit on your next purchase anyway. But they’ve raised the minimum to $5.