Carbonite's lowest tier plan, Safe Basic, runs $6.00 /month ($71.99 /year). There are two higher tiers available as well, called Safe Plus and Safe Prime, and run $9.34 /month ($111.99 /year) and $12.50 /month ($149.99 /year), respectively. Each tier is a bit cheaper if two or three years is paid upfront. Plus, they each have a few extras over the base service like external hard drive and mirror image support.
Most services encrypt your files with strong systems such as AES 256 before sending them up to the servers over an encrypted connection. The majority of products we tested also offer a private encryption key option. If you choose to manage your own encryption keys (basically the "key" that decrypts your backup), know that it is your responsibility to remember it. The online backup service itself will not be able to help you reset the password if you forget it. On the flip side, this means that no one (including employees of the backup service and law enforcement officials) other than you can unlock your backups. This is ideal from a privacy and security standpoint. Use a password manager to keep track of your private encryption key if you think you will forget it.