the exact replicas from the movie are the funko ones which are available at Entertainment Earth, Amazon, Hot Topic, etc.
the one that's only available on eBay is a promotional pin that Disney and Chevrolet have been giving at events like New York Comic-Con and for riding Test Track at WDW. the design of the promotional pin is what we saw on the teaser posters, but it's not in the actual movie.
I bought mine from EntertainmentEarth (mentioned above) for $4.99. I got one like Frank gets from the 1964 World's Fair and the one Casey gets years later. The cost was about $14 with shipping and the second one was backordered, so Amazon Prime would be a good way to go since it's a little bit less for the same pins.
My son is going to DLR in a few weeks and was hoping to find a Tomorrowland pin, but I may tell him to just order it from Amazon before he goes. And no, I'm not giving him mine
When we went in april they were sold out. Day we got back I was on disneystore website and there they were. Limit 1 of each kind per customer. Worth it. Kiddo loves it!