I think if your house/company burned down and you loose yor main PC and the external backup, you'd be glad to pay 0.10 cents for every Gigabyte you can retrieve.
Or potentially higher than 20x that much, if you are downloading it quickly (are you actually aware of the Glacier pricing model? where did you obtain $.10/GB?).
But it's not like S3 and no backup at all are the only two options. There's loads of backup providers (Carbonite, Mozy, Backblaze etc) out there. The comparison needs to be against those.
https://news.ycombinator.com/item?id=7337181