Most upper brand name Mig welders are vary well built and I would have no problem with a used unit .But new or used some of the low buck units have so many problems they are hard to use. To almost impossible to use .I am mostly directing the problems to the 110 volt models .A friend who dose not weld gave me a Cheap 110 volt low amp unit ,wire feed through the hose type . He played with it a little and quit . Thinking he just did not have the feel for welding ,Almost like a person playing the piano, but in reality the machine was so bad it took real skill to make it do any work at all .And aluminum welding is out of the picture all the way ..The first issue the unit did not have a on and off switch for the power to the wire .The gun switch only ran the wire feed . This makes things real sparky from the git go .And you spark the wire on your work a lot when you are not ready . This is really something you need to know ,If what you are thinking about dose not have a power to the welding wire off and on with the wire feed DON"T even think about it pilgrim .ASK if you are not sure and if seller can't tell you walk out the door ( I was able to over come this problem with a old foot switch that pluged into the 110 outlet then the machine pluged into the foot switch and shut the machine off when not held down with your foot but its still not a good way to run the cheap thing).Also the cheap thing had a low duty cycle and over heated so bad that it poped the fuse all the time ,I added a small cooling fan inside the unit to keep the wires inside from melting . Now it is always best to buy a tool made in the country that you live in . Welding systems will smoke some parts, Tigs will burn out parts at the torch end  , and its part of the game . You just live with it . Migs are no different ,hose tubes go bad as well as gun cups and gun wire guides .So why on earth would you buy a unit made in China or Europe if you live in the USA or Canada , It makes good sense to buy a unit that you can get parts for,and you will need them ,"local" .Not on the other side of planet earth ,or maybe not at all if from Asia . If you smoke a $5 part then your unit is gone ,now a bargain unit is far from a bargain now . .Next issue, The unit need as much adjustment on power as you can get .The cheap unit had two adjustments in a high range and two in low .Flip switches ! thats another bad thing . The unit could only run at a few wire speeds due to lack of power adjustment . This makes the user over move or under move with the gun .And you can't work at your own speed ,you work at the units speed . Thats Bad REAL BAD . Unit must have a rotating type power adjustment . made the same as the wire feed adjustment .Now we come to the Ground wire and the gun hose .I know you are thinking the unit is light and is EZ to move . but the longer the hose and ground wire the better . use one of the cheap units and you will find that out fast .If I only had a few bucks I would much rather have a used Miller,Hobart or Lincoln than a new import , I don't live in China or Italy . And last Buy as much power as you can ,a used unit with 130 amps is far better than a new unit same brand at120 amps . And better yet try to find a unit that can work with 110 volt and flip to220 volts with one inturnal switch . I know the high end Lincoln 110 volt unit will flip to 220. Do your homework and you will get a unit you can  work with ,something you can't use right or is scraped due to a smoked $5 part is worthless . If you go used ,pick it up your self and make sure it works . Also a starving welder dealer sold me a new unit with a little black dirt on the gun . Salesman ran it for about 15 min . As a demo . Got a fine unit for the price of  factory seconds or lower grade model unusable type at Builders Home Low end Depot Harbor China Sales & Easternwood Mail Order cat. If you want to save a buck never mind smoked up ,paint chips , Blackened gun The first time you will use it ,it will get smoked up anyhow .Thats the place to save cash ,not Amps and adjustments and power switches. Good Luck All and please vote on this ,how did you like it .