Sony "won E3" in a lot of ways, chief among them the PS4's price tag. At $399, it's a full $100 cheaper than the Xbox One, and that makes a big difference to a lot of people.
The Xbox One is more expensive because every console includes a Kinect sensor. The PS4 features a new PlayStation Camera, but unlike Kinect, it's not included by default. So Sony kept the price down and made fans happy.