This dress with accessories was worn on screen by Claire during the "prom" scenes and can be clearly seen on screen during multiple scenes.  Won during Premiere Props live auction. 

$99

Michael's (Kelly Blatz) Bloody tuxedo

This is Michael's Bloody tux, the one he dies in at the hands of the killer.  It is the only screen-matched bloody tux that surfaced from the film. The ensemble includes the tux jacket and pants, plus the screen-matched bloody shirt.  COA from Premiere Props

Below is the definitive screen-match on the shirt.  You can match every stain.