Finally, numbers other than picodollars and gigabyte months and unpredictable deduplication. This convinces me I don't want to store 4TB there at a huge cost($12,000 if it's really $300 a year for 100GB) compared to buying two 4TB drives (~€250 per 3-4 years) and placing them at a friend's with free bandwidth.
Don't get me wrong: managed, off-site encrypted backups are very attractive, and I might be willing to pay a premium, especially for software from a trusted person, but not the cost price hundredfold.
Tarsnap isn't intended to be used as one-time backup like that, and it's super expensive if used that way. It's very cheap when used to backup (almost) the same 4GB for 1000 days in a row, which is what a lot of people/businesses need for their backup solutions.
I guess, I haven't really looked at it yet. And I'd have to find my own software to encrypt it before uploading. Tarsnap's software is one of the major selling points, at least to me.
Don't get me wrong: managed, off-site encrypted backups are very attractive, and I might be willing to pay a premium, especially for software from a trusted person, but not the cost price hundredfold.