So you want to buy a TIG welder,

There are a few pitfalls for new comers to tig machines ,

First ask your self what you want to weld with it,

Do you want to weld Aluminium ?

Tig welders come in AC/DC or DC

AC/ DC tig will weld aluminium, DC will not under nornal circumstances. 

 The reason why AC will weld aluminium has to do with the AC wave form  having the ability to clean the hard layer of oxidation from the surface of the aluminium as the polarity reverses during the cycle firing electrons at the surface layer and lifting away the oxidation in the process.

Welding aluminium with DC is possible but not recomended .