http://www.amazon.com/Army-Custom-Airsoft-Mask-Black/dp/B008BEFKMA/ref=sr_1_1?ie=UTF8&qid=1383143131&sr=8-1&keywords=deathstroke+mask then commence to painting... but you're going to hit a serious snag. Time. I know this one is like $98, but I just did a quick amazon search.
Short budget and 6 days before an event, costs and shipping are going to eat you alive to get them on time.
Are the Halloween Express or Spirit stores open around you? You might find something there, or just keep hunting for Airsoft Masks (Some nice ones in the $30 range) and find one you can get shipped in a hurry...
Sorry I'm not more help.