You'll be spending a little extra over time, but the upfront investment is nice and cheap.
Microsoft's $99 Xbox 360/Kinect bundle has finally left the Microsoft store and entered retail locations. Both Best Buy and GameStop are now carrying the bundle, which gets you into an Xbox 360 at an incredibly low initial investment of $99. The catch, of course, is that you'll be paying a two year subscription fee at $15 a month.
The end cost of the system and the Xbox Live subscription comes to $460, which is not too terribly much more than if you bought the 360 at a normal price and got cheap Xbox Live vouchers online. The price difference is between $60 and $100, but for folks that don't want to – or can't – spend $300 on a system up front, this might be a nice way to go.