I'll chime in with my $.02 worth.
I had a Century 145 mig for about 10 years. I ran the daylights out of that thing and it finally gave up (fried cooling fan). It could have been repaired, but the cost would be pretty high to still have a 10 year old welder. About that time, TSC had a smoking hot deal on the HH 180 in a kit package that included the welder, cart, a small gas bottle, wire, gloves, chipping hammer, wire brush, and a decent auto-dark helmet. I don't remember the exact cost at the time, but I think it was in the $500-600 range. After Christmas, they started cutting the price to move them out. Unfortunately, the local store was sold out prior to the cut and I had to travel a ways to get mine, but at under $500 (I don't remember the exact price anymore) it was well worth it. I have been very happy with the machine, the taps are nice. (the Century was infinate and sometimes very tempermental to find the "sweet spot" on certain jobs.) It is also interesting to note that the gun has "miller" embossed right on the collar so clearly there is some interchange of parts. The portability of this machine is a bit of a joke as it takes a pretty good man to lug it around by the suitcase handle on top. I'd guess it must be close to 100#. For what I paid, I didn't think I could go wrong, and I don't think I did. Long story short, if you can wait, keep an eye on TSC around the holidays, they may run a similar special again.