I read on a post HauntForum that Costco had some oversize masks for sale. I stopped in today during lunch and sure enough they had this huge Don Post witch mask for $24.90. There were others as well but I need to add another witch to my scene this year to make it a trio. This mask should be a nice basis for the last one.
However, these are not Death Studios type masks. It is low quality latex and has cutouts for the mouth, nose and eyes. But for less than $25 it should suffice.
The skull in the picture is there to give it some scale. The mask is quite large.