The closest equivalent I can think of immediately is Amazon Glacier, which is intended for 'long-term' storage where they take care of transferring the data as

The closest equivalent I can think of immediately is Amazon Glacier, which is intended for 'long-term' storage where they take care of transferring the data as necessary to preserve its accessibility. Obviously they're thinking years-to-decades, not centuries, but as a ballpark it may work. Their current pricing is $0.0007 per GB-month, or $0.000064 per KB for 800 years in today's dollars. Since the Latin text of Magna Carta is 28 KB of UTF-8 text, that works out to $0.0018 to store the text for 800 years. You'd obviously also want a high-resolution scan of the original document. I don't know how big that would be. If it was a 100MB image, it would cost $6.66 to store for 800 years at Amazon's current Glacier prices. Obviously we're making immense assumptions about the reliability of the service, of price stability to deliver the quality of service, and so on. And perhaps the biggest issue with this analysis is that we're also relying on huge economies of scale for it to be profitable to deliver an archival service like this over centuries. If this sounds crazy cheap to you, you're not alone. As technologists we're used to dealing with huge volumes of data, so it's easy to forget that historically these volumes simply did not exist.