alt Hacker News15 years ago I was an intern at Micron and learned they passed on a contract with Apple because Apple insisted on discounts and there wasn't a compelling reason to reduce profit at Micron.
So yeah, Apple probably does pay less. But the market has enough demand that suppliers do say no.
This is actually relevant, because DRAM costs just as much now per Gb as it did 15 years ago (that's controlling for inflation; it's as much as it cost 20 years ago on a pure price basis).