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.
If they bundled the item with a pack of batteries in a retail store and sold it for 39.99, would you still consider it cheaper?
Would you consider $39.99 cheaper than $45?