I've been collecting art and memorabilia for a long time and I can assure you that you would get one cheaper if you were prepared to wait... but you might wait quite a few years before you find one that you really like in the condition that's acceptable and it might not be the exact North Shore one you've convinced yourself you really want (it might be a "City and Eastern Suburbs" or perhaps a Newcastle roll instead).
One thing I've learned from collecting over the years is: Don't pay too much even though you might fall in love.
The primary reason for that is that things go in and out of fashion and if you buy something at the height of its fashion-ability and pay top dollar, you might find in ten or twenty years that you've lost money. Example: Walnut-veneered art deco 1930's furniture was red-hot about 15 years ago and you could pay some ridiculous prices for things like sideboards with lead-lighting. It's right out of fashion now; teak Danish 1960's stuff (the sort of thing you used to see a lot at hard-rubbish night twenty years ago) is now all the rage and you could find yourself paying many thousands for a long, low sideboard from the sixties but unable to get anything like the thousand dollars that you paid for the deco sideboard bought years ago. Train and tram memorabilia is exactly the same proposition.
Tram destination scrolls are very, very fashionable right now, as evidenced by the many hundreds of imitations you find in cheap designer places and on E-bay. There was a reproduction tram scroll on "The Block" recently; that should be your warning sign that the market is hot and interest is very high - it might not be that way in another five years.