Totally cute scarf! I'm just finishing one in Moonlight Mohair (which was only $1.99/ball at my Michaels) for a charity auction my boss is collecting donations for.
But the MATH!!!
90 sts to start, then you double them, to 180!! Then double that to 360!! The double that to 720!!
No wonder it's taking me three days to bind off. :)
An aside: We're getting a cold front and it's beautiful outside!