It sounds like a souvenir made for gift shop purchase going back more than 10 (maybe 20?) years ago, based on the close dates of the casinos you named. I don't recall seeing anything like it.

I agree with Bob M. to check with Spinetti's. At least they had it at one time. I doubt that Bonanza gifts would have it, as they have LOTS of current / recent souvenir stuff, but not likely something this old.

Other places to try: There are a number of thrift stores, 2nd hand stores, and especially Vintage & Antique stores & malls in the Las Vegas area. It's a needle in a haystack, and something you'd have to invest the time in personally, as you can't just call someone. But ... it may be out there somewhere.

Actually, there are a few LV Antique Store/Mall "specialists" out there that you might be able to hire as a "picker" to be on the lookout for your item. I don't live there, so it's not me, but ask around to see if any LV residents who make the rounds to Antique stores might help you (for a commission, of course). Just an idea.

On a different but related subject, here's an odd piece that I have with 12 different casino names on it. A dodecagon (I had to look it up). Just showing it; not for sale.