We have a nice option in Sydney at least of owning your own Argon or Argoshield gas Cylinders,So no more rent to pay.
Up front cost is about $330.00 for a D size and about $460.00 for an E size,All sizes are available and for fabrication shops that use a fair ammount of Gas there is free delivery from Mona vale.
http://speedgas.com.au/argon.htmlAs for a Welder why not consider a 170 Amp Cigweld Inverter multi process machine being lighter is always a bonus,Parts availability and Service Locally beats Chinese made stuff.
Then there is the advantage of being a Mig welder for light Aluminium welding ( No Tig I know but usefull) A DC stick welding option and a DC Tig also in the one Machine makes a Good Choice they also do bigger than 170 Amps but these can be had for about a Grand or so so are good value for home use.
Unimig also have similar Inverter multi process machines,I would not buy a Conventional Mig these days unless a quality second hand machine for a good price such as a Miller,Lincoln,Cig,Esab,Unimig or WIA brand.
And of them the Esab is best avoided as service and parts are becoming difficult as the company seems to concerntrate on Plasma cutters these days.
Personal experience owning Migs from CIG,Lincoln and Miller and having used the others as well as Kempi and Lincoln Tigs also owned and soon to add a Gigweld Tig to the Mix.