Given how cheap USB Flash Memory Sticks are today (128GB for $10, 256GB for $20) and their small size along with "Offline Ruggedness" that is probably your best and cheapest long term backup resource. They are cheap enough that you can make multiple copies of the same backups then distribute them in different physical locations as needed. Here is the sobering reality for a lot of people. The bulk of their data that consists of important documents and stuff like that is very small. Usually way less than 1GB for most people. The vast majority of the large space consuming content comes from Multi-Media data such as Pictures, Movies, Programs, Cell Phone Backups, and stuff like that. It's easy for us to be lazy in administering our Multi-Media content. But the reality is that we don't need 9790834234028309 pictures or movies of random stuff that accumulates on most of our PC's, Phones, Tablets or whatever devices we use on a regular basis. Taking the time to sort through the saved Multi-Media data on our devices and deleting what really isn't needed will dramatically reduce your backup footprint.

The hardest part for the average person is knowing what is really important to backup and what is not. There is a tremendous amount of bloat in applications these days so backing up a whole PC can consume a lot of disk space. This is where you need to pick the level of data administration you are willing to live with. I would rather backup unique data onto cheap USB Sticks then accept the fact that if my PC's hard drive takes a dump I will need to manually reload the OS and all of the applications then restore the unique data as needed. Some people don't want that level of data administration or manual rebuilding effort so they backup everything, which requires a high quality (and expensive) external hard drive or RAID of a size that is usually 2x - 5x the size of their PC's hard drive. It basically comes down to this... Ease of Use/Administration = Backup Solution Cost $$$$ or Not so easy Use/Administration = Backup Solution Cost $. Also consider that your time and effort is also worth something in $$$ as well. If my PC's HD fails and I have to manually rebuild it from scratch on a new HD that is usually a full day worth of work to complete. Everyone's time is worth something in $$$ so in the long run it is probably better to spend the extra money up front for a more costly backup solution so its less time consuming to recover from when it does fail.