Mig welding is fairly easy. Just takes a little practice and learning how to set it up for whatever material thickness your working with. For a beginner you don't really need anything fancy. I just bought one of these:
Cheap Ebay welder for $180 to use in my office at work. Its the cheapest 110V welder I can find that can do DCEN. (Direct Current Electrode Negative) It's an OK welder. Its no match for my Lincoln 140C or my Miller 180, but for a welder I don't care about that sits in the corner of my office most of the time, it performs well. I've been able to weld 3/16 with .035 flux core, and if I add a regulator, some CO2/argon with .023 or .030 I can weld down to 22/24ga sheet. I don't think much of the stepped voltage, and its only capable of 10% duty cycle (bad). It does a good job on common automotive 16Ga through 20Ga on gas, and is perfect for 1/8 angle when on DCEN flux core.
The advice I strongly emphasize, is if you get one of these EBay specials that include the face shield, and hammer, THROW THOSE AWAY right out of the box and get a proper helmet, thick gloves, and proper slag hammer. My MINIMUM for safety is Forney brand gloves, helmet, and wire. They are cheap money wise, available at most Napa Auto parts stores welding isle. Oh and junk the weld wire they come with too.. Lincoln, Forney, or Mathesons wire is the way to go.
I think for my office welding set up including safety, I spent a grand total of $350. I think I'm the only I.T. manager in the western hemisphere who has to weld repair his own office once in a while.
Are you gonna build bridges and sky scrapers, or patch holes in battleships with one of these 110V jobs? NO.
Are you gonna be able to patch rust holes in van bodies, or make roof racks, van bumpers, spare tire or bike carriers, and the such? YES.