You do not need a high voltage source if you are making an electric vaporizer. Using a suitable low voltage element, high current is what’s needed. Although a 12v high current source can kill if you're wet and salty, it is much safer than 240v.
Using an auto cigarette lighter assembly hooked up to a switch (at least 20amp rated) and a car battery works. A suitable high current power supply such as a 12v radio transmitter PS may also work. Some old CB or Ham 12v supplies were rated at ~20amps. Higher current supplies will work, providing the voltage doesn’t exceed the rating of the element
A variation on this can also be made from a modified soldering iron.
Or there is always the poor mans vaporizer
The tips of 2 old table knives are heated to red/orange over a gas hotplate. Rolled up bud, hash, whatever is placed on one knife and compressed with the other. Smoke is inhaled at a SAFE DISTANCE from the knives through a paper tube or funnel.
For safety sake, a straight operator should work the knives. A long tube from an Al foil roll is good, and allows the smoke time to cool.
If you slightly under-heat the knives, the smoldering produces vapors of the oils. The lower temp (lower than a flame) helps prevent the THC from decomposing and therefore produces a cleaner smoke containing less carcinogens- in theory anyway.