Construction costs
I purchased a more powerful electric soldering iron and subsequently also had to invest in a gas-powered one to be able to solder the heavy lugs on to the high-voltage cables. This drove the overall cost of making the burner higher. However, both will undoubtedly be used in other projects as well, so it is inappropriate to add the cost of these items to this particular project alone.
The most expensive parts I had to buy were the double-pole doublethrow switch and the pilot light, which together set me back around A$50. The 2m of high-voltage cable cost around A$10 and the microwave cost A$8 from my local tip shop. The two jumper-lead alligator clips added another A$25 to the total cost and the bell-press switches A$40. The box and other bits and pieces I already had lying around the shed. As a rough estimate it would cost less than A$150 (NZ$164) to buy all the bits needed, and considerably less if you simplified, or left out, some of the added safety features that I incorporated into my unit. I could have eliminated the doublepole double-throw switch and the pilot light and just relied on the two bell-press switches to deactivate the transformer.
For the budget conscious, most of the examples I saw on YouTube were mounted in open wooden boxes. These are not suitable, as they allow contact with the mains, so you should consider a lid to make sure the box doesn’t get wet, or you don’t inadvertently place any metal tools, etc., across the open side!
I am more cautious, and opted for the enclosed Bakelite unit, making it impossible to accidentally contact the transformer or inadvertently loosen any connections. All the 240V wires running between various components are completely enclosed and the only remaining hazard is the two probes coming out of the unit when it is switched on.
Frequently moving the probes, doing only shortduration burns, and carefully controlling the saturation level give you control over how deeply the tracks are burnt in the timber