I started using CO2 only and it seemed cheaper, but its not. Once you swallow the pill and rent big Argon mix bottle you will wonder why you have not done it on first place. Not to speak of that i need not clean additionally the job. And believe me, it took me all day only cleaning spatter, when i welded my machine.

But to make things easier:
-brush parts around with oil prior to welding. As i said i use olive oil. So the spatter will not stick to the oiled part.
-dip the clean Mig gun every 10 min into the oil while welding. That will help keep it clean all day.