fair enough, the clothing coming from the show is fascinated, "different", but deffinitely costume worthy....
she often wears cute, short dresses with leather jacket,
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OR: theres the cute tanktops, etc....
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and, this isn't Buffy in the picture, but the uniform is the same, you can go for a "sunnydale high" cheerleading costume:
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either that, or, my personaly favourite, find a hot, brooding, sexy guy, and hang onto his elbow the whole time (this guy would be angel) :D ...
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heh lol, hope this helps, and hope its not too late :)
have fun, x