Flux core might be your best bet, produces deeper penetration than Mig, easier than stick to do and if you're proficient, you can produce decent looking welds. I would rather have a name brand used machine, saves you money and you can still get it serviced at electrical repair shop. My local shop won't even look at the off brand stuff, too many headaches and lack of parts support.
**Get a good Welding respirator, your Lungs and Brain will thank you in years to come. Welding fumes are nothing to take lightly.