Just bought a Nelson industrial for like $8. It has appears to be all metal, including end that gilmour recently made plastic. It's also rubber over moulded so should minimize damage to car paint when ddropped. I found it at menards.
Why in the world would you ever want a cheap tap set? Have you ever broke a tap off in something? That is an unpleasant experience I would try to avoid by starting with quality tools. I am a HF hater. There are two store I will not ever shop in, HF and Walmart.
Braze and flow the inside of the joint with nitrogen gas to avoid corrosion. This is how medical air lines are done. YouTube video "braze without nitrogen vs with nitrogen". Great vid.