The one on eBay is a BuyItNow ask price. These should be worth about melt value as they are not scarce. They sometimes go for $50-75 to people who buy the name and age of the piece not having knowledge of the relative scarcity. Also, a pristine proof piece will bring more than a used token with lots of dings and handling marks.

I don't know whether this piece specifically was used in the slot machines but many silver hi-denomination tokens were so used as recently a a year or so ago.