You can make one yourself for under £20, all you need is a base and a (25mm or 30mm diameter) solid stainless steel bar the right length off ebay. A drill, some glue.
The weight of the steel stops it falling off easily if you knock it off the side or shelf or mantel.
I made myself a few in no time. These are two different ones.
You could use an epoxy putty to attach the steel to the skull, after chizeling a tight square underneath the skull for the bar to fit.