Blackblaze wanted to provide unlimited storage to their customers for $5/month.
After looking at several overpriced commercial solutions, we decided to build our own custom Backblaze Storage Pods: 67 terabyte 4U servers for $7,867.
Here they detail their process. You can even download a 3D model of their Storage Pod.
A long time ago we stopped measuring storage in our datacenter in gigabytes or terabytes and started measuring in petabytes.
$5/month for unlimited storage is a tall order, but met with ingenuity.