From my experience, it's worth the extra cash if you can find a good deal on a Miller/Lincoln/Hobart. My ex father in law got a good deal on a display model Hobart Handler 140 (I think it's a 140...not sure). I've used it for flux core wire and gas shielded MIG, for .010" sheet metal to 3/16" barstock, and it's done well with all of it.
Anything high-power electronics from Harbor Freight scares me. I love their hand tools and whatnot, but I've had too many power drills melt, burst into flames, etc, that I stay away from their welders.
Dustin
Port Washington, WI