$30 at Amazon. The reviews on this are so hilarious that I'm considering purchasing it myself.
White Horse Mask with Detachable Bridle in leather by HawkandDeer
This Leather Pony Mask Demonstrates Stylish Apocalypse Fashion trendhunter.com
DIY Halloween masks Make your own Horse Mask by MiesmesaBerni
horse head mask horses headdresses white mask cinderella
Fuck yeah, horse masks!!
Horse mask printable coloring page for kids
This is a tutorial on how to make a kick-ass beautiful horse tail for your masquerade or halloween costume as shown in the image. It will take a lot of time and patience and I warn you, dont get into this unless you are dedicated! ;)
Horse mask templates including a coloring page version of the mask. Free printable PDF at http://maskspot.com/download/horse-mask/
Horse Mask PDF Pattern by oxeyedaisey on Etsy, $5.50