Obviously they paid more in storage in the past than today and it is a different solution but if you were to buy 50 PetaBytes today in one of Backblaze's Storage Pod 6.0s it would be $1,750,000.
And there is ongoing maintenance & costs of drive failures.
I feel the need to donate to Internet Archive soon, as I have greatly benefited from it in the past and am sure to in the future too!
Total used storage: 50 PetaBytes
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https://archive.org/web/petabox.php
A few highlights from the Petabox storage system:
Density: 1.4 PetaBytes / rack
Power consumption: 3 KW / PetaByte
No Air Conditioning, instead use excess heat to help heat the building.
Raw Numbers as of August 2014:
4 data centers, 550 nodes, 20,000 spinning disks
Wayback Machine: 9.6 PetaBytes
Books/Music/Video Collections: 9.8 PetaBytes
Unique data: 18.5 PetaBytes
Total used storage: 50 PetaBytes