I haven't seen any for sale? I made a couple of different molds with silicon rubber that work quite well. One was a copy of the cell cups that come from the nicot system and the other are cups I got from Rossman.
Because of that thin lip that Michael mentioned, the molds need to be warmed before pouring the wax so that it doesn't cool the wax before that small cavity is filled.
The molds makes about 20 or 25 each. Of course the mold could be made to make as many as you would like in a run.
It was just something to try at the time that I made them. But turned out that I make all my wax cups with those molds now.
"Success is not final, failure is not fatal: it is the courage to continue that counts." Winston Churchill