My guess is around 30-45k. Halloween has passed by a few months, we're in 2016, and it's not easy to come by right now. Hope this helped!
Do you mean Headless Horseman Mask? There has been 2 releases of that head. The only Haunted Head was in 2013 is worth much more then the others. The Haunted Head is a pumpkin and the others are jack-o-lanterns. The Headless Horseman Mask are probably worth 25-40k.