I have also seen these made out of nickels. As for value, there is a whole bunch of collectors that just collect exposition memorabilia and prices would be different for every exposition. As for the "coin" value you would need to be able to see the date, but on this one you can't. It could be a 1877 or just a common date hopefully the latter.
My daughter collects elongated cents but she has nothing like that. I remember a few years ago on another forum someone was selling one of these from cairo street (or some street, not sure what street it was) and it was supposed to be super rare and it sold for allot more then I thought it would. I didn't realize there were that many elongated collectors out there that was willing to pay what those worlds fair coins sell for but the history behind the coins is what makes them so fascinating to me
That is strange no image of the coin details appear on the EC. I collect them and I do roll them when I go to parks, museums, aquariums, etc of places I visit and there is always an image on one or both sides.