Some of the cnc's are great tools. I think they can be fascinating. I have heard of far too many problems with the carvewright (however it is spelled), but the more expensive ones can be quite good.
In my opinion though, if you are looking to start any kind of business, the more important part is developing a product that will sell and a market to sell it in. If you accomplish those two things, then the tool and technology for you production will naturally follow. If all you have is a faster way to make the same things, then someone else will always find a way to make it even faster and cheaper.