Any ideas on how to make about 25 affordable jail costumes?

I am doing a cl competition and there are about 25 of us doing it. We want to dress up as prisoners and be in a cage...and we have this reallly cool performance in mind.... But we need a way to find or make about 25 very affordable jail jumpsuits (this cannot be tacky! It has to look almost professional because we want to win!) and ideas for both the cage and the costumes? anything would help- any links or suggestions! thanks!