Very curious that only two replies mentioned a non-US coin. I would have expected more.
I cannot say I really have a Holy Grail coin which I desire. I am happy to get what I can find. I do have a couple of items which I have picked up along the way and which I am happy to own:
A 1702 Queen Anne threepence of UK in XF condition and a 1899 Morgan Dollar in G condition. Why am I so glad to have the latter? Because in G4 is listed in the catalog at $130 and I found it in a roll of culled dollars I bought at spot price.
I also have a Morgan dated 1848, obviously altered, but an interesting talking point as it looks perfect.6 years ago