Hm? let me look again...
I'll save you the trouble
![](http://i.imgur.com/oQog5bz.png)
Not everyone gets it. Unboxing or crafting only
No, literally everyone gets it, and there's no way to unbox it
The Unusual Horseless Headless Horsemann's Headtaker is crafted from Haunted Metal Scrap, an item you obtain from completing the "Gored!" achievement, which is possible in any server that has the Horseless Headless Horsemann enabled
That being said, the only person who would actually buy one would be a collector or someone who used their Haunted Metal Scrap to craft a hat instead and still wanted the Headtaker