It's fruit day in the Japanese video game industry! Sony sent out apples to the press to promote Gravity Daze, and 5pb. and Kadokawa Games followed by announcing that the PS3 version of Steins;Gate will come with bananas.
While Sony's apples were real apples, the banana bunch that comes with Steins;Gate is just a toy. The item is based around an in-game item.
You'll only get the banana toy if you buy the game's Double Pack, which includes both Steins;Gate games. This is priced ¥14,000.