Thank you for all your help and info! I'll keep looking. I only have the stock photo to go by, so if anyone here has pictures of the real deal they would share, I'd be grateful. I don't even know what size it should be. This one is smaller and lighter than I thought it would be, but that's just speculation as I've never seen one in person. This one is 1 3/8" from nose to tail.
I think the size of the metal one is smaller than the leather charms, just comparing it to the size of the keyring. Measuring to the outer edges, Coach keyrings are about 1.25 inches across, and the dog on Coach's keyring looks to be almost the same size as the keyring.
I don't remember even seeing one on Ebay before although there may have been a few. If you're heart's not set on the metal one, they also did a larger Jack Russell in leather, I remember seeing one on Bonanza recently, unless that was another breed of terrier. It's bigger and you don't have to worry about the enamel chipping off. It won't have a red coat but at least you don't have to worry about it being counterfeit.