that's a ridiculous comparison. just some of the many, many things you forgot about,
1. a backup mechanism, that probably involves multiple other drives and a computer
2. networking hardware and a broadband connection (if you are talking about parity w/ drive)
3. electricity to power all this stuff 24x7. just the electricity to power the rig is going to be around $20 / month.
4. your time maintaining the whole setup