Yes, because the sacrifice is part of the activation cost, not part of the effect you've countered.
Wow, cool.
Now that makes Stifle just as nice as Teferi's Responce
Thanks!
Against a wasteland Teferi's Responce is indeed better (even if it costs a bit more), but Stiffle is way more useful, since it can be used against a bunch of effects: fetchlands, storm effects, memory jar, worldgorger dragon... and many more. A wonderful card against lot of T1 decks.