Hmm, interesting question......
Depends on the day; my moods fluctuate quite a bit, and what I'd be willing to sacrifice directly varies by my mood. For example, I just read the last of the series, which made me so depressed that I'd be willing to do sacrifice about anything material to get a bird morph. Red-tailed hawk, as a sort of remembrance of Tobias.
On good days, though, I'd be less likely to say "yes", regardless of whether a sacrifice is involved or not.
If I was in the situation the Animorphs were in - given the power to save the world, with a very real crisis in progress - I'd say "yes" regardless of the sacrifice.