I found two options that seem like they could lower my monthly bills compared to Amazon Glacier, which is $11 per month for a Terabyte… I currently have my Synology set to backup all data to Glacier, where I pay for everything that I use.
iDrive (called HiDrive in the Synology Package Manager) https://www.idrive.com/pricing is $3.71 per month (with current discounts) for 1TB of backup directly from your NAS. It seems like the most straight-forward way to get backups for about 1/3rd the price of Glacier. I will need to try that option out.
And then there is Symform… http://www.symform.com/how-it-works/features/
Depending on how you set up your backups, it could be free, especially if you’re willing to foot the cost for drive capacity that exceeds your needs by a ratio of 2:1. My one concern is if someone manages to both break the encryption of the distributed file chunks as well as gains the ability to reassemble whole files or search across their network. I just don’t know if the threat surface on your data is actually higher with the distributed nature of their storage scheme. This will require more research, but in theory I love the way their service works.