The guy who had the original prop piece, (without the whip attached,) attempted to sell it on e-bay a few months back. It didn't sell. I didn't have the cash at the time, or I would have tried to snatch it up.
I contacted him later to find out if he still had it, and he didn't, which was a pity, as I know the guy who made the majority of the whips for the Rundown, and would have commissioned one from him to attach to the handle.
My understanding is that the handles were made from steel pipe or rod stock that then had the grooves, knucklerings, and the monkey heads sculpted to them from resin.
-Dan