Never mind the cost, the time is even worse!
With most imaging programs it is possible to restore partitions one by one even if it is an image of a whole disk.
backup FROM my DVD, I boot to it. THEN make all my backups to my 2nd HD which is 500 gig drive. Your of course all right using dvd's would be rather stupid. Sorry guys, brain was not working that day, too many hours on puter.
DVD's, that contain all your data files, can easily be stored in a fireproof vault or Off Premises for safety.
But as has been reported, doing a whole drive backup to DVD's is not only expensive but terribly time consuming.
In most cases with a desktop PC, a second internal hard drive, say in the 1TB size range makes a great place to back up your C: drive and it's the fastest too.
For years I've used Ghost 11.5 * to back up my C: drive (it includes the boot sector) to an internal Hard Drive and as a second backup. I use a 1TB USB 3.0 external HD. I also use FAST Compression, which saves a lot of space on my storage drive.
The best backup plans should be impervious to fire, theft and acts of nature (hurricanes, tornadoes, lightning, and floods).
Anything less is just a waste of time, money and electrons.
* Ghost 11.5 is the last DOS based Backup Program, that is compatible with all OS's from 98 to Win-10. I always run it from either a Boot CD or a Bootable Flash Drive.
Remember..... the only BAD Backup is the one you decided NOT to make.
Being the old paranoid type, I have a 9TB RAID 6 disk to do my backups to, so I have several previous images of both system and data. From time to time I copy a system & data image to a single HD for off-site storage (more like off-case storage in my case ).
My solution is to keep a spare hdd containing my most valuable data in a drawer at the office. I update the the backups on this disk approximately once a month. This way I would not lose my most important data in case of a fire etc even though there might be a slight loss the most recent changes since I don't update the backups more frequently.