Rare as hens teeth in any condition and you will likely have more chance of scaring up a used one from someone here with a rashed or busted one that hasn't thrown it away.
Making your own seems practical, plenty of rubber gloves etc of different thicknesses that could be used to source the rubber.
But... just realized that mine is stretched out worse'n Betty White's wedding tackle, so I'll have to do some cipherin' off the original parts to figure out what size I need.