With welders it seems you get what you pay for... IF you get lucky and get a good chinese welder that dosn't need repairs it will probably be fine. The problem with the import welders is getting parts and support when needed. If you get a Lincoln or a Miller the support is great, and they are decent machines. If you want a starter machine get one of the small suit case inverter models from Lincoln or Miller, true they are a scratch start, but they give good bang for the buck (my dad just bought the Miller for stick, and really likes it). The next step up would be Miller's econotig, and for a little more omph the 185 from Lincoln (this is what I own).
The 3 in 1 is probably a scratch start tig and a touch start plasma. Touch start plasma won't work all that well for cnc.
I have yet to regret spending a little more money and getting a better tool. Even If you need to save up a little while longer, my advice is to do it and get the better tool.