I'm a TIG welder by trade and I use a Migatronic or a Fronius everyday, they are Both DC only but are well over £3000 each so would not even consider buying either for home use.
For use at home in the garage I'd look at something like this:
http://www.frost.co.uk/eastwood-tig-...dc-welder.html
I don't know how good it is but seems about the right price for a decent hobby set