Feel free to disagree with me, but I think Halloween is quite stupid. Being of pagan origin, and connected to the harvest season in the northern hemisphere, it obviously doesn't have much to do with us. But then carnival is all brazilian, and is quite stupid too, imho.
Anyway, it's getting more and more popular here, I guess. I first heard about english schools here celebrating the occasion, but now it seems to be more widespread - to private houses and clubs, for instance.
Plastic wigs and fangs that are sold for a few dollars in the US can be found here at Lojas Americanas for something like R$30.00.
I have to confess that I'm planning on buying myself a very big afro wig that I think will look cool on my head, but I think I'll wait for the post-holiday sale. Please don't go buy them now, or they'll run out of stock soon, thank you.