I need a Halloween costume(a cheap one)?

i'm going to a halloween party with my friends, one is going as slutty school girl, one as mrs lovett from sweeney todd, the other as a cat. i'm 18, i want a costume, preferably cheap cos i'm not working at moment, i want it to be y but not so y that my dad would lock me in so i couldn't go. it would be great if it was clothes i have already with accessories. please help and include pics if possible.