Profit margins on computers are surprisingly small, with too many companies doing the "wal-mart" and insisting on quarter/quarter price reductions. Unfortunately, to be competitive, you have to factor that into the initial cost to even get the business in the first place. Not sure about drives, but the profit margin on DRAM is INCREDIBLY small. To pay for the R&D you must make a massive investment- enough so that most of the tech of the silicon is actually purchased intellectual property- and everyone is buying the tech from the same design companies.
The day of massively profitable computer companies is long gone- you have to take the profits early and not look back to even survive in the market. As individual consumers, we are helped along by the early adopters that paid the high prices when the tech was young- we get 80% of the performance of the current top-of-the-line, but at 25% of the cost.
As I think about it, another place where the big companies have to spend is for warranty and service. If a company is offering a warranty, be assured, the cost of it is factored into the initial price. When you build your own PC, you're really taking on the costs of much of the warranty.