Low cost to insert, low cost to keep it there, high cost to retrieve is exactly the combination you want when looking at disaster backup solutions, since you do

Low cost to insert, low cost to keep it there, high cost to retrieve is exactly the combination you want when looking at disaster backup solutions, since you don't intend to retrieve the data frequently. Buy some earthquake insurance (I know, easier said than done) and only pay for 1/20 of the retrieval cost.