I started with a $150 115V Century Flux Cored welder, that was about the size of a twelve pack. Used the snot out of it for over 4 years. It had a high and low setting, and I left it on high for 99.9% of the time. The only problems I encountered were running it until the thermal overload switch clicked, and running out of wire 15 minutes after Home Depot closed! Yes the welds looked like crap, but none ever broke once I got the hang of it. And I was able to weld thick stuff, too. I just had to make multiple passes and build up the weld fillet to do it. Now, the kids down the street from me use it, that way they won't wake me up at 8 o'clock on Saturday to get me to weld their motorcycles back together!
Several years ago, I bought a Miller 251 MIG unit, and it is NICE..
That may be a little overkill for what you want, and a little expensise ($1900 or so) though.
Miller currently makes a mid-size welder where you can switch between 115V and 230V input voltage by simply changing the quick connect plugs. I think that model is around $1K or so, but don't quote me.
Miller also makes a 210 MIG welder, where you can buy it with both a regular gun, and an attached spool gun, which you can use for aluminum!! Again, this might be a little expensive, 2 grand, or thereabouts.
Their website has all the details.
www.millerwelds.com There are also some very nice welding instructions in the library section on their site.
Anyway, don't be afraid to be a tightwad and buy an el cheapo unit to learn on. If it breaks, gets stolen, or you suddenly lose interest, it wasn't that costly. However, when you get good at it, the price increase to a full size MIG unit doesn't seem so bad anymore...
Also, check with a local welding supply house, they may have a rental unit or trade in at a serious discount.
Last, but certainly not least: GET A GOOD HELMET!! You only get one pair of eyes!
Andy