There are many sources for used equipment in excellent condition but be sure that they are reputable. For example, a couple of years ago I purchased 30 year old 350mm Hasselblad lens that is excellent from a dealer in NY (with a return policy) for $750 - a new one was about $7000.
I immediately checked that the apertures and shutter speeds were accurate and they were right on. Do some homework you might get very lucky.
Had no problems for more than 25 years with the standard screen on my 500C. Heard about the new Acute-Matte being something extraordinary. Asked my repairmen if he could fit in such a A-M screen (500C having no interchangeable screens, came with the C/M model). He wasn't very impressed by the A-M: yes, bright but not necessarily easier to focus with compared to a screen with a very tight cut frenel lens. I followed his advice and he put in this very nice screen with very tight cut frenel rings.
Have now a A-M screen to my 2000FC/M and my 500ELX. I think he was right: the A-M is lighter, at least a 1/2 step, perhaps even more, but I would vote for the screen in my 500C when it's about easy focusing. Unfortunately, I don't know from where my man got this nice tight cut frenel lens - as I understand it’s not an original Hasselblad screen.
On the other hand, the A-M screen is also very nice to work with! Personally I prefer a clean screen (no prism etc.) and the plastic piece with 1 cm square net put on top of the screen.
Yes: www.araxfoto.com. Gevorg Vartanyan (the boss) is a very nice fellow: feel free to use my name if you like!
Philippe - just received my new focusing screen from Arax today - I installed it on the spot, and it works so much better than the standard Hasselblad one, the split circle really does make focusing easier. And, at $24 incl shipping, incredible value for money. Thanks for letting me know!
"We are much more likely to act our way into a new way of thinking than think our way into a new way of acting." - R. Pascale