According to eBay listings for iPhones with Flappy Bird installed on them, it seems they are going for quite a pretty penny. One is listed for as much as $100k. That said, it’s hard to say whether that’s a legitimate bid, or if sellers are artificially increasing their bids.
It does sound like a lot for an iPhone 5S with a game installed.
Flappy Bird was a wildly popular iPhone game that wasn’t even good. However, it somehow really took off, and people were all over it. The sudden popularity came unexpectedly for the developer, and for unknown reasons other than the surge in recognition, he decided to pull the game. He gave people a chance to download it, but it’s gone now. Seems people who didn’t download it want the game now, and if the prices aren’t a hoax, they are willing to pay some serious cash.