If this is the case,
the next question is< on average what is the cost of a good used CNC machine?
as for business what kind of income are we talking about?
Prices and income capabilities are pretty much all over the place, and depend a LOT on what there is for local opportunity too.
I bought, for instance, a mid 90's vintage Milltronics knee mill for $1600. I got lucky. I have seen similar and better sell for a LOT more. Even after paying more than that to truck it home, I am in under the value of the component parts as spares.
Lathes, sorta that way too. I would not buy a CNC lathe with a hope to make money with it, unless the lathe was so cheap as to make it a no-brainer, or unless I had an opportunity smacking me upside the head to get my attention. Or, the best reason of all, because I just wanted too.
A CNC machine can be used in hand wheel or jog mode to do some manual work, but it's awkward and not very comfortable until you are very familiar with the particular machine. There is a distinct lack of 'feel' to doing work this way.
CNC has it's place. If you don't mind putting the time in to programming, and become comfortable with it, esp if using a CAD/CAM program with a decent visual simulator or cut path render feature, you can make very complicated parts the first time through.
Or you can wreck stuff at the push of a button. But once you get yourself sorted out, it becomes pretty easy to do those repeat jobs.
Check out the various machine tools sales sites around the web. Many many of them are simply trolling for contacts for the sales guys to work over, but some guys actually do list prices. If you live in the sticks and have no particular local industry, chances of stumbling upon a great bargain are pretty remote. Lots of machines for sale on Ebay too. Worth a look for the price of an education. Check out places like KBC Tools and Thomas Skinner, Knuth , and whoever else you run across.
Cheers
Trev