There's no way that Apple pays spot. They will have contracts directly with the manufacturers, guaranteeing them a given supply at a given price. Their whole business kinda depends on it.
Sure, but eventually the contracts will be renewed at possibly a much higher price. It depends on the details of the agreement whether the price is adjusted based on market price periodically too.
If I have a potato field, the cost to me of a potato is whatever equipment and labor it takes to farm one, divided by the yield of potatoes.
If there's suddenly a potato famine, then the cost to other people who don't have a potato field is however much they are willing to pay to avoid starving.
Apple doesn't have a potato field, but what they do have is a ton of negotiating power, market share, and enduring relationships with the manufacturers.
There's also the implicit threat when negotiating with Apple that they might enter your market if you fuck around with them. If Apple perceived DRAM/NAND prices to be a significant threat to their carefully curated pricing structure, they might decide that they need to vertically integrate.
