I just use plain ol' white styrofoam dinner plates. You know, those ones that come in a bag of like 200 at Wal-Mart for about 3 or 4 bucks? I just draw a spot in the middle with a black Sharpie about the size of a quarter or nickel.
They are just about the size of a human head and sternum area. I figure, if I can keep 'em all on one of them, I'm ok.
+1...'Cept I'm even cheaper...I just use the absolute cheapest paper plates they have.