What's your budget? I picked up a cheap chinese tig/arc welder off ebay a long while back for around £500. Same as this one.

http://www.ebay.co.uk/itm/4IN1-AC-DC...item25a5b69897

Although that pack is better because it has the foot pedal which I've been meaning to get for mine. Used it on titanium and steel, haven't needed aluminium welding but have no doubt it would do the job.