It’s definitely a truism that the absolute cost of storage, measured per GB has continued to drop steadily over the last 15 years. In fact, when I was involved in purchasing storage hardware it was common to put in place a quarterly price reduction of around 5% on any long-term deals. Prices have dropped over time because the disk manufacturers have been able to continue to increase the capacity of data stored in a standard drive form-factor, delivering more capacity for the same physical amount of space, power and cooling.