somewhere in this blog and in my own photo collection is a couple of images of a woman posed like a mannequin in a window with a plastic mask. it turns out the mask is the frount part of a styrofoam head and have been around for some time. a link to a few on ebay were posted by someone in comments. they definately have an stylised almost cartoon look too them but work well imho.
after one of my random ebay searches through mannequins in ebay last week i found a similiar styled plastic mannequin head though with a much more realistic look too them. you can get them it sets of three from this listing here.