Help! Halloween Costume Ideas Needed

I'm going to a costumes-required Halloween party this Saturday, and can't think of anything to wear. My criteria are that I don't want to spend a lot of money ($25 max) and, well, I don't want to look like a ho. Which, after stopping by one of those Halloween pop-up shops last night where everything was either scarily skanky-looking or incredibly overpriced, might be a trickier goal than I'd initially thought.

I loved The Glamourai's post about DIY costumes based on movie characters though weirdly I don't have any of those items in my closet (note to self: must get a Hepburn-esque classic black shift). I'm this close to throwing on an old white bed sheet and calling myself a ghost, but maybe you guys have some more original--but equally easy to replicate--ideas?? Definitely let me know if so!