But isn't that the point? You pay a low fee for inconvenient access to storage in the hope you never need it. If you have a drive failure you'd likely want to restore it all. In which case the bulk restore isn't terrible in pricing and the other option is, losing your data.

I guess the question of whether this is a service for you is how often you expect a NAS (that likely has redundancy) to fail, be stolen, destroyed etc. I would expect it to be less often than once every 5 years. If the price to store 12TB for 5 years and then restore 12TB after 5 years is less than the storage on other providers, then that's a win, right? The bigger thing to consider is whether you're happy to wait for the data to become available. But for a backup of data you want back and can wait for it's probably still good value. Using the 12TB example.

Backblaze, simple cost. $6x12 = $72/month which over a 5-year period would be $4320. Depending on whether upload was fast enough to incur some fees on the number of operations during backup and restore might push that up a bit. But not by any noticeable amount, I think.

For amazon glacier I priced up (I think correctly, their pricing is overly complicated) two modes. Flexible access and deep archive. The latter is probably suitable for a NAS backup. Although of course you can only really add to it, and not easily remove/adjust files. So over time, your total stored would likely exceed the amount you actually want to keep. Some complex "diff" techniques could probably be utilised here to minimise this waste.

Deep archive
12288 put requests @ $0.05 = $614.40
Storage 12288GB per month = $12.17 x 60 = $729.91
12288 get requests @ $0.0004 = $4.92
12288GB retrieval @ $0.0025 / GB x 12288 = $30.72 (if bulk possible)
12288GB retrieval @ $0.02 / GB x 12288 = $245.76 (if bulk not possible)

Total: $1379.95 / $1594.99

Flexible
12288 put requests @ $0.03 = $368.64
Storage 12288GB per month = $44.24 x 60 = $2654.21
12288 get requests @ $0.0004 = $4.92
12288GB retrieval @ $0.01 / GB x 12288 = $122.88

Total: $3150.65

In my mind, if you just want to push large files you're storing on a high capacity NAS somewhere they can be restored on some rainy day sometime in the future, deep archive can work for you. I do wonder though, if they're storing this stuff offline on tape or something similar, how they bring back all your data at once. But, that seems to me to be their problem and not the user's.

Do let me know if I got any of the above wrong. This is just based on the tables on the S3 pricing site.