The stuffsack for the Endurance for me has been bombproof and i have 2 of them, taken a hell of a beating over the past year and its still in as good a condition as it was the day i bought it.
Only thing that annoys me is that its soooo hard to get the sleeping bag back into the sack, takes about 20 minutes if your lucky.
As for the availability, a few places have them left, you just need to dig around.