In reply to MikeR:
Yep, thats the way forward, somewhere like machine mart you could get a clarke MIG for around 200. I'd recommend a gas set up as the gassless ones tend to be very smoky and spattler a lot. Gas can be either a lease of a 'big' pub size cylinder which could be costly but would last a long time if you were doing other jobs that paid cash. The small disposable gas bottles are about a tenner each and last an hour if lucky but that said, if you only connect it and open the valve during actual welding they can last a long time. The thing with welding cars is that you have to accept your initial estimate usually turns into double the area and work you first thought it was! You also need to be fairly competent with a spanner, indeed you'll need a comprehensive tool kit plus a load of other stuff too - left, right and centre snips, loads of small G clamps and mole grips, flap wheels and drill and an angle grinder with cutting and grinding wheels. A decent pair of gauntlets, overalls and helmet is needed too. An auto darkening helmet are the dogs but don't skimp on a cheap one - you only have one set of eyes.
I used to look for MOT failures where the failure points were structure / welding and bought and sold many, many cars and welded em up and got em MOT'd with my rig. It has paid for itself many times over. I have even had my own car wrote off after I did the welding - the mrs got t-boned by a 4x4 at 40mph 2 years ago in a mondeo I'd replaced both sills on. I went to look at it in the compaound afterwards and not one of the seams I'd welded had spilt so a huge confidence booster.
Heres an example of what can be done fairly easily at home:
http://s786.beta.photobucket.com/user/blanchie14c/library/Wheel%20arch%20re...