Back in 1977 or 1978, I remember my dad and I riding down to a nearby major city to pick up one box of ten 8″ diskettes. I remember they were SS/DD (single-sided, double-density) Nashua 
brand with a formatted capacity of about 230k under CP/M. The trip was justified because they were a great deal at $50 for the box.
That was $50 for a total 2.3 MB of storage.
For a simple comparison, my BlackBerry Playbook, a full computing device with input and output, is thinner than 5 discs and certainly smaller and has 64 GB of built-in storage. It would have taken over 291,000 SS/DD 8″ disks to reach 64 GB. Of course, one could upgrade to DS/DD 8″ disks and cut that around 146,000 disks.
(And don’t forget, we now have 64 GB MicroSDXC cards that are (roughly)
Looking at it from the dollars perspective, using www.measuringworth.com, that works out to about $175 in 2013 money, about the cost of a tablet today. For 2.3 Megs! To reach 64 GB back then, it would have cost over 1.4 million dollars.
Just thought it was an interesting observation.