I've been thinking & its time i sorted out my tools, seen as all i have is a very basic set now, i did have all the tool's i needed but wrong decision's made me end up with no tools

ok I'm after a mig welder around the 180amp mark, i dont really want to go any lower in amp's,
i would go & buy a new one but i dont have that sort of cash, so it's down to getting a used one.
i've seen a few on trademe that are in my price range just wrong timing, i'll have $600 to spend, but not untill another 5 weeks time will i have the full 600 cash on me so thats were the tricky bit is, but i dont mind waiting & it gives me the time to suss one out,
the main reason i'm after one @ 180amps is it will cover all the welding i'll have to do for chassis work n so forth & i also want to be able to use it for tacking up ali, i've got a few idea's about stuff i want to make out of ali for the landy
any help is always much appreciated
Dave