Clarke welder

[skov]

I've got a Clarke 130TE, which is fine for the chassis tubes, and borderline man enough for 3mm plates.
I think you want to be looking for a welder that will do at least 120 to 130A (although like deezee says, much more than that and it won't run off a 13A plug).
If you go for a second hand one budget a tenner or so for a new liner. I was amazed what difference it made changing mine.