Seems like bandwidth costs would kill this, restoring a TB is $120 in bandwidth alone, then you have the retrieval fee.
I agree with some others that the cheapest for now is buying more HD and keeping them in sync with crashplan or something else, until Google Drive drops a bit further in price for 1tb.
I do a rotation of hard drives in my house. I think it would be useful for the "my house burns down" scenario. In other words, I will probably never need the restore, but if I do, cost really isn't an issue.
Don't forget buying a separate facility to store your extra hard drives and your time regularly doing full restoration tests to confirm that you haven't been hit by silent bitrot.
I agree with some others that the cheapest for now is buying more HD and keeping them in sync with crashplan or something else, until Google Drive drops a bit further in price for 1tb.