I think you'll get the same advice over and over here, get the best welder you can.
I did a course at the local college last year and bought an old 180amp mig, I use pub gas instead of argon mix because you can get a big CO2 cylinder for £15 and it's not like I'm doing any fancy work or pretty work so I am happy to live with it.
I'll tell you what though, you'll end up just looking around for crap to weld, it's fun. Make a topgear sofa and get a picture up here