@Siswell: It a small local supplier to me, unfortunately his supplies are erratic at best. If you find them online (I havent) try to get the MID code before you buy as Datawrite have a habit of either switching media codes (but not packaging) or dropping to landfill quality.
@Jarthel: All media degrades, some quicker than others. Just keep important stuff in dark (most important) and dry conditions and it will last much longer.
If you scan important stuff regulary, you should be able to catch pending failures long before you lose anything. Obviously real crap media already start from such a low point that any degradation tend to mean you going to lose data. Had very little G04 fail on me, except for half a dozen which for some reason developed physical cracks at the hub. Most G04 scans almost as good as when burnt, a few seem to improve even.