Miller high frequency arc start

Not sure I'd pay that kind of money for that, given the overall price of some pulse tigs nowadays. You are nearly 1/3 of your way to the price of one, maybe more if you buy a used TIG

It depends on what you are going to do. I bought an old Century arc stabilizer pretty cheap, and already had an AC/ DC stick box, and a neighbor gave me a permanent loan of a bottle, so I got in pretty cheap

But here's the deal..........You don't really need an HF box to TIG steel.

Google up "scratch start"

And, one of these won't give you the fine control you need to weld light ga. aluminum.

Seems to me your 4 bills could be better spent