Well the OP is talking about welding aluminum, so that is that
If you are just starting, and happy with only steel, you can use a "scratch start" hobbled together out of an AC/DC stick machine, which are cheap and easy to get used. You can even weld steel (I'm told) without an HF device........only a stick welder, a tig torch, and a bottle and regulator.
This guy here is the go-to tips guy far's I'm concerned......