this is an excellant website if you want to teach yourself mig welding,http://www.mig-welding.co.uk/,and it gives tips on how you can upgrade your mig,i use the small portapack brazing kit as i cant justify the rental costs of the oxy/acet bottles
and i use pub gas for my mig,it spits a bit but good enough on thin steel,i get it from the bloke mext door ,who's a fitter for guiness,one bottle has lasted for ages now.
the website gives good reviews on equipment from people that have used them,dont know if this applys to downunder,i was contemplating buying a small tig,but learning something else,having not mastered mig yet seemed a waste of money.and then theres alloy welding !!!!