toaster: ... Most blank discs available in NZ will not last more than 12 months ...

I have blank discs older than this, and every disc I have burnt to is still readable. In fact most don't have a single scratch.

I've got discs that are around 10yrs old and still work fine. Most of them were the cheapest I could find at the time.
I do agree though that HDD storage is currently the best way to go although I have had two HDD failures in the last 16 yrs. No storage method is perfect.