Here's a site where you can buy it online, although it looks like they only have a couple of iPhone sizes available, and the price is in pounds, so the shipping to the US might be steep.
All other info I'm finding — including on that site — suggests it's supposed to be exclusive to the parks, so that one might have been purchased at D-Tech and is being sold, hopefully unopened, third-party. I'm not familiar with that site, so buyer beware.