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.
iFixit has their own store.
I know, I only took this specific screenshot because it happened to show up as a recommendation within Amazon’s interface and I noticed the price and discount seemed odd. I intend to try buying it (or at least, a similar set made by iFixit) on their own site when I end up actually needing it.