personnaly, i won't go with a cnc machine to start, if you don t know the basic of metal fabrication. how you can program a cnc mill effectively if you don t know the proper to attach a piece to the table or the step you do to start with a rough piece and the finish with the piece with all the good tolerance.
also, in the paintball industry, i think that starting a all new gun is a very difficult business, you can t sell a copy of a gun without having the risk of pursuit.
and if you think at Doc, he live from that and he doesn't have a cnc machine. you can do every think you want with a manual machine, it will only be harder and longer. when you think at that, baefore the invention of CNC, the machinist was making the same piece as now.
personnaly, i will go for manual machine, but for only 10000$, you won t have a lot of equipement, like HTRN said before, having a machine shop is very expensive, if you need to buy every thing from the lathe and milling to the shop towel, you will need more than 10000$. you can use all this to only get the tool for the machine