If money wasnīt an issue and I had to chose between a brand new 503cw for 4k$ and a Millenium Edition for 3k$ then I would go with the new one, since the Millenium was 12 year ago and I would rather pay 1k more to make sure I have a pristine camera instead of spending a lot on a camera of which I donīt know how it has been treated. I would also prefer to buy from a friend rather than online and from someone I donīt know. In case something should be wrong with the camera during guarantee time (this is another important point) you can bring it back to the shop. With an used camera, you either wonīt have guarantee or problems might occur if you have ordered it online (dealer can refuse to take it back, repairs might be unsatisfying ect. these are worst case scenarios of course).
I donīt have 4k to spend on a Hasselblad however, so I myself would look for a nice 501cm ;-)
What about the lenses? If you want to buy these new, it will come pretty expensive. Maybe your friend can give a discount if you order a lens with the body?