I bought a Home Depot 175. Middle grade on sale. For about half the price of a Hobart. I occasionally pop a (220 V) 15 AMP fuse at higher settings.
Noticed that the insides of many welders are the same pieces or close enough not to make much difference. The brand name they sell them under can be different. Most of the major welder manufactures produce, contract welders for many of the local retailers, Wal.Mart, Home Depot etc. They slap there name on there, maybe another color. I hang out for the sales. Can often save a couple of hundred bucks. A six step heat range and an ifinitely adjustable wire feed are really all thats necessary. The more electronics the higher the cost. Though a constant AMP system does have it´s benefits, AMP/heat changes as the material heats, you can either adjust with technique or buy a machine that adjusts for you. A spot weld timer, is also nice.
A bayonet hose, wire, pistol assembly is nice, can switch from large pistol to small pistol quick. Metal wire feed rollers and tensioners, are also something else to watch for, last better than the plastic.
Much of your welding can be done with, straight C02, the Argon mixes are used for cleaner welds, but cost double. If you know anybody in the resurant business, the same bottles used for the coke machine (with a regulator), work well for sheet metal work. If you buy your own bottles, the refills for the larger bottles are often close to the same as for the smaller bottles. Double the bottle size, doesn´t mean twice as much to refill, shop around. I get my refills from Home depot, cheaper than by the wholesaler. My local Home depot, doesn´t charge for bottle inspection and tags or inspection stamps.
Check for the availability of teflon inserts for your hoses, if you want to weld, non-ferrous metals sometime.
An auto dimming mask is also nice, but pricey.