Maybe US$20-US$30 is a more likely figure. Most (or all) of the HDD manufacturers use components made by others like all ODD manufacturers so there's a very clear limit to cost-saving. If Google email users have a total number of 1 billion accounts... and each account has an average 1MB files... that's still only 1PB requiring 2,000 500GB HDDs (for US$200K?). Almost anyone in the West perhaps can have that much at home if there's that much storage necessity.