I got bitten really badly by this a while ago when trying to migrate some servers about.
3TB of storage would cost £21/month just to have it sat in Glacier. This isn't too bad, I suppose, but when you then need retrieve it, you're looking at an additional £270.
That depends, because you can actually recover it for free over a long enough time period. It's easy if you plan your file sizes in advance based on your allowance, and don't need it in a hurry.
Your bill is based on your peak retrieval rate multiplied by the number of hours in the month.
But you can retrieve a calculable amount an hour, for free, all month, for however long it takes to get your files back. You could also pay a little bit more, and get them back much after.
You certainly wouldn't want to request all 3TB at once though.(It would be billed spread over four hours, and it'd still be thousands.)
You can request ranges of files, so even if you have massive files, you can still throttle the requests to below a given threshold if you're careful.
Never seen the snowball before -it's shiny looking hardware. No idea what the actual cost works out like, though. 1 petabyte per week they claim...
At the moment I'd be interested in backing up my NAS boxes, which is only about 36tb raw or 23tb usable space. It's a lot, but nowhere near snowball sizes :)
3TB of storage would cost £21/month just to have it sat in Glacier. This isn't too bad, I suppose, but when you then need retrieve it, you're looking at an additional £270.