Here's a link to a welder I found on ebay that would easliy do the trick.
However it requires a 230v 30 amp outlet which should'nt be to hard to wire up if you have easy acess to your breaker box.
Your gonna want at least 140 amp or higher for good penetration and preferable a gas type mig. The good name brands like lincoln, hobart and miller are also the ones you'll want to buy, shy away from the no name cheapo's welders. Hobart makes a 140 amp 115 mig thats as good as a 115 unit you can buy but it would be border line for good penetration on 3/16 and thicker and only has a 20% duty cycle. The link below would be my first choice and it has a 30% duty cycle.
Goodluck, Charles
http://cgi.ebay.com/LINCOLN-POWER-MI...QQcmdZViewItem