What welder to buy
Go to cyberweld.com and check out their Hobart 140AMP MIG. Their pricces are great too and free shipping!
I have a lincoln 135 with a tap switch and it works great for everything you would want to do on a car. If you're trying to weld anything thick (over 3/16), just make sure you bevel the ends so you can get good penetration.
Goodluck!