buy mig. I wouldn't buy the last two.
You are going to really need a gas bottle and regulator to do sheetmetal cleanly.
Look for a lincoln sp135+, millermatic 135 or a hobart handler 130-140. Better machines and should at least have a regulator with it.
A $40 hf auto dark is easier to use than that hand held pos that comes with the lincoln. If you aren't skilled, it's tough to one hand it while mig welding. You're going to spend another $200ish above welder cost to get set up (bottle, mask, gloves, cart).
