Buy the biggest welder you can afford with the money you can spend.

The difference between a 110v and even the 175/180 class 220v machines is huge. There's MUCH more to a welder than the material thickness it's capable of welding.

The ONLY reasons IMHO to buy a 110v machine are 1) cash 2) portability 3) lack of 220v service. Service is easy to put in. Portability isn't a big deal unless you plan on dragging it to friends to weld. Cash is the biggest issue.

You can find a complete 1-3 yo Miller 175/180 with tank/cart and occasionally helmet for around 450-750. Just have to look. Craigslist is a good place to start. There's a Lincoln 250 in Tulsa for $700

And the comment about it's just for this... never works out the way... You'll end up doing other projects that require more oooomph. DAMHIK!