I also have read up about using a mig.
You need to run a trimix gas (argon, co2, helium) and use it with ally wire or s/s wire depending on applicaition.

I believe that you can use your standard mig shield (arogn, co2) with a proper tig

The chinese units that you see about.
They list all the specs of the known brands, and some offer better specs, for significantly less.
Some people, like above say, yeah fine.
Some say, you get awsome units and some crap units. its a lottery.
Some say. just keep away from them. Crap, with no spare parts available and unrepairable.

For me, i want to make sure that what ever i buy its the right tool. If that means you have to spend some real cash, then i just have to save up. Buying something at half the prie only to have to replace it sooner, is not cost effective.