I'd think that the Deadringer movie is in deed the
Holy Grail for any Meat fan or Meat collector (There's a clear distinction and the two aren't mutually exclusive. Many Meat fans don't avidly collect).
As has been said Eva released a number of items within the fan community when she liquidated her collection a few years ago. Some more desirable than others, dependinhg on personal taste. For example the Helping Hands whilst a one off item wouldn't be somethign I'd personally be interested in, wheras the signed bass guitar was.
I'd have thought the original painting which features on the WTTN cover was a very desirable item to many collectors, but luckily for me it turned out I was the only bidder.
For me personally the Zimbabwean Bat II and the two early seventies singles are the items that I'd most want to add to my collection. Although the new album is a must find as well when it's released