Grand Prix and Space Odyssey are EASY to locate and would not be much of a challenge. They are more "sentimental" machines for you ?
I was keen on your interpretation of a "Holy Grail" pinball.
I suppose I don't really have a 'Grail pin' at the moment
I have bought a NIB Stern
I will have the limited edition when WOZ comes out
Most games prior to '74 do not interst me much (but a 'Teachers Pet' is on my 'wants' list)
Everything else will come up for sale at one time or another
I suppose a proto-type game would be cool, but one would have to import it from the USA,
(eight ball deluxe or Flash Gordon with the bigger blue displays)