One of each at a minimum.
More if it were things like Battlepacks or TARDIS exteriors (as I would LOVE to have one for each Doctor...And non-canon Doctors...And each modular...And-)
Listen. I have 24 (or more) real Cybermen figures. I would happily triple that in LEGO form.
Daleks it entirely depends. Cult of Skaro and Imperials? Yes please! Skaro MK2 Travel Machines? Sure, I'd like a few. Renegades, Rainbows? Maybe a few.
If it were things like interiors and setpieces, it, again, depends.
If they redone the Ideas set, I'd grab another so I could colour-swap the Time Roter to make it orange like Capaldi, if they done Tens, I'd probably buy that twice to make a Paradox Machine.