The above post does not consider one very important aspect - the skill & experience needed to do a decent job with the welder. I mention this because I've walked that road - sitting on a shelf in my home office is a little Campbell Hausfeld wire feed welder, hood, gloves, etc., I installed a dedicated 20A circuit for it. - there's even a box of scrap sheet (off cuts from my local exhaust shop) to practice on. I've welded exactly one thing on my car (custom brackets for an LED light bar), it's a heck of a lot easier and quicker to get the guys at the exhaust shop to do what I need done, and not have to worry about proper penetration, etc.
Essentially unless you're using the welder frequently, there's a good chance that your welds are going to be weak and crappy.