Go spend a hundred or two on an external drive, then use something like CarbonCopyCloner (great) or Deja Vu (my choice, easier to control) to automatically backup. My iMac wakes up at 6:00AM each day, 10 minutes before I do, and makes a full backup of all user libraries and documents folders. Just to be safe it does a weekly backup in a separate location.
I intend to have my files, come hell or high water 🙂