I make my own. Paraffin is cheap and saw dust is easy to find. I fill up a 48-egg carton with saw dust, then melt the paraffin and pour it over the saw dust. Let it cool and cut the egg container into individual eggs and store them in a zip lock bag. My last batch I made about 150 of them and it cost me next to nothing.
Weber Spirit E-320, UDS with IQue 110, Orange Thermapen, Maverick ET-732