buying good caster monk stuff is not a waste at all, as it is same as mage's requirements.
and if you buy caster staff, your warlock gears are automatically set.
even if you have caster dagger, you can go straight to caster ninja

about difficulties it's quite similar to caster rogue, except usable gears are more limited.
melee monk is horrible when you failed to find a good cata team @ 60+...
i passed monk/ninja as 30(40)-71 caster and currently love a pure (1-71) casting class.
