On the about page for the Mountains of Madness expansion it states that you will need 5 green packs and 3 yellow packs ( http://www.fantasyflightgames.com/edge_npm_sec.asp?eidm=250&esem=1 ). However, having sleeved Eldritch Horror and Foresaken Lore I have a lot of sleeves left over. Using the contents provided in the Mountains of Madness rulebook ( http://www.fantasyflightgames.com/ffg_content/eldritch-horror/EH03-%20Mountains%20of%20Madness/EH03-Rulebook.pdf ) I've tallied up the actual number of cards in the game so you can plan your sleeving accordingly:

Large: 10 (8 Investigators, 2 Ancient Ones)

Standard/Green: 210 (26 Mythos, 14 Mystery, 12 Adventure, 6 Prelude, 4 Round Overviews, 4 General Encounter, 4 Americas, 4 Europe, 4 Asia/Australia, 6 Expedition, 6 Other World, 48 Research, 24 Special Encounter, 16 Outpost, 16 Mountains, 16 Antarctica)

Small/Yellow: 114 (8 Artifact, 16 Asset, 16 Spells, 42 Unique Assets, 32 Conditions)

Personally I have 43 unused green sleeves and 60 unused yellow ones (clearly I've overbought the yellow ones in the past). There are 50 sleeves in each new pack. Based on this, I only need sleeves for the following:

Green: 210 (MoM) - 43 (spare) = 157, or 4 packs (and 43 spare).

Yellow: 114 (MoM) - 60 (spare) = 54, or 2 packs (with 46 spare).

Hopefully this will help out people who have a load of spare sleeves left from EH/FL or other games.