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.
They do, but I’ve also seen it the other way around, where the price on Amazon is the price on the manufacturers site plus shipping. Usually for more reputable/niche products. IFixit I would’ve thought would be big/popular enough to do that but I guess not.