Re: welders
Well, Keoke's suggestion is the most logical, but what's the fun in that!?
My first MIG (now on my 4th) was an Italian Silver Beauty; eighty (80) amps of metal-warming thunder__downhill! I actually did ALL the floor/rocker/sill work on my Healey with that unit, along with teaching myself to weld (this was 1986). I'd give anything to have my first welder/welding project NOT be my car, but all this time later, everything is still holding up just fine.
As far as a welder is concerned, a decent__name brand__will retain a fair anount of its original value, assuming it's been kept relatively clean and not abused. Miller makes a very good quality 110V unit, and it would handle just about anything you could hope to weld on an automobile (a 1/2" thick trailer hitch would be beyond its capabilities though).
Buy a decent welder, use it for what you need, and if you don't think you'll use it again, sell it on for a minimal loss.
Whatever brand of MIG you decide to go with, I strongly recommend you get one that is set up for use with a shielding gas. The flux-core type wire (no shielding gas required) produces some bad-ugly welds__even if they do hold, you wouldn't be very proud to show them off.
I've made some pretty good buys on new equipment through the "stores" on ebay...