I'll throw some tips out to you guys who may be in the market for a new machine or are just info hungry.
Buy the best one you can afford. That sounds like simple common sense but don't fool yourself. Sure, you can get a bargain deal from the Craftsman catalog for $350, but what happens when it acts up, or you need tips, or a new liner for the gun? You gotta call them, or take it to the service center which you probably don't even have in your area.
Even if you only plan on using it occasionally(unlike myself who feeds my family by it). Get one from a welding supply store, Arcet, and National Welders are nation wide and I'll bet have a location near you.
Miller,Hobart, and Lincoln are the most popular and have the best support among welding suppliers. The popular models are often on sale and can be had a great discounts over regular retail.
An exception is the Hobart Handler line of machines that can be bought from discount tool supply stores like Harbour Freight. Hobart is now owned by Miller. The Hobart Handler 135 is one of the finest in its class of welders. Usually for under $500 you can pick one of these up at just about any welding supply store ar discount tool store. Basically all of the big welder companies have comperable machines in each class. Expect to pay about $500 for a descent 110 volt machine that you can plug in anywhere. The 220 volt machines usually start in the neighborhood of $800-900, and go WAY up from there. My shop just purchased a Lincoln Power MIG 300 which is a pulsing DC power source with a built in wire feeder. It can be used to TIG, and Stick weld as well as MIG. With a special push-pull wire feeding system(required for welding aluminum) this thing cost $5000. That is with just the MIG set-up, not including the TIG and stick accesories. But as I said, my baby needs formula, so we do what we gotta do.
What are you going to weld? Steel and stainless have no problems being welded with a standard MIG machine and gun, that is what they are designed for. When it comes to welding aluminum, that is when it gets specialized. Special "Spool guns" are available for most 220V welders that holds the spool of aluminum wire in the handle. These for the most part work OK. I have used a Millermatic 250 with a 30A Spool gun for about 5 years now. This is Millers top of the line spool gun. It is very tempermental as are ALL spool guns. Tips get burned, it's heavy since it has a 1lb spool of wire hanging off the back of it, and it has a 30 ft long 00 gauge power cable going to it, along with a gas line, and some low voltage wires, it's a bundle. BUT, this sort of thing is REQUIRED if you want to be able to use the same machine to weld steel and aluminum. I have a 30Lb spool of steel wire in the regular wire feeder and gun, and then the SEPERATE spool gun that uses the machine as its power source only. A set-up like that will cost about $2500. Aluminum requires more heat(voltage) to weld than steel since it is a better heat sink. So, welding aluminum with a 110 volt machine will be a huge PITA, if you can even do it. Then, the Push-pull feeders I spoke about earlier are "THE WAY" for welding aluminum, but require you to change 30lb spools of wire if you want to switch between steel and aluminum. Push-Pull guns are available as up-grades to most 220V machines. Some name brands are Cobra, and Python which are named after what they look like. They look like snake heads since they have a set of drive rolls(wire feeders)hidden in the handle. I hope this helps anyone that is in the market for a welding machine, or you can just use this info to impress the guy who does your welding