Damn. I've only gotten 3 so far. O_o
For the fury I think you should use Arena (although you probably have your own tactic. )
And yeah, I THINK the best way is to get very far in the Arena, when I got to wave 30 in Arena A I received around 5000 each boss zombie.
If you're persistent enough, I guess you could get this after a LOT of Arena.
I doubt I'll ever get all myself.