Prices for External Drives are getting less and less expensive nowadays. I recently got a 500GB external drive for less than $150. It uses a USB cable and can be hooked up to any computer. That is my main and permanent back up, not only for photos but for the main computer and music as well.
Then, I use DVDs/CDs to copy what I often like to view. If it scratches, I still have my main back up to make another one.
That external drive goes into a fire/water resistant safe box for storage when not in use.