Hi
It would probably be much cheaper and more likely to achieve an accuracy of 3 microns if you buy somthing like a Jones and Shipman cylindrical grinder and modify it to suit your needs. Most cylindrical grinders would be at least a tonne, there are a couple of Myfords mg12 on Ebay at the moment (255kg according to a website i checked). These mg12 machines can be fitted with a boring spindle which is mounted where the Myford plate is fitted.
Colin