I have XR3 Pro for mill and the cost for upgrade to XR4 given to me a few weeks ago was $750. I didn't upgrade yet. I did end up buying the basic two axis lathe package for $1800 though. I know I probably didn't need it, but I can create programs in CAM with almost no effort. I won't even bother G coding a facing operation anymore. I am hoping to upgrade the XR3 mill I have early next year.