Adam,
I use candle wax. I go to boot fairs and buy all the large church type candles that I can see, you get them for not a lot.
I have an electric hotplate, a camping gas cooker is not too expensive otherwise your SWMBO might let you use the kitchen stove top. I also have an old Turkey cooking oven tray, plenty big enough for most sizes I cut down to.
But there is a problem, the paraffin wax used to make the candles, has sterine in it, which makes it brittle, e.g. it will crack when the wood shrinks. The answer to that is to add some bees wax to the melt to return the flexibility to it.