Super fast math with assumptions (nothing more than 20 cards per faction):
Base set: 8 factions @ 20 cards each = 160 cards
7 Expansions: 4 factions = 80 x 7
Big Geeky Box: 2 factions = 40
160 + 560 + 40 = 760
So 800 sleeves should cover it, 900 if you think you might tear a bunch.
Edit: Apparently the base cards are the same size so add two of those per faction = 16 + 56 + 4 = 76; 760+76 = 836
Edit2: The Munchkin box comes with monster (20) and treasure cards (22). The Cthulhu box comes with madness cards (30). 836+20+22+30 = 908 so go ahead and buy a cool 1k and that should have you covered!
160 + 560 + 40 = 760
So 800 sleeves should cover it, 900 if you think you might tear a bunch.
Edit: Apparently the base cards are the same size so add two of those per faction = 16 + 56 + 4 = 76; 760+76 = 836 Edit2: The Munchkin box comes with monster (20) and treasure cards (22). The Cthulhu box comes with madness cards (30). 836+20+22+30 = 908 so go ahead and buy a cool 1k and that should have you covered!