Assuming you're in the US (by your usage of 'cell phone' and 'data plan'), I have no idea. I'm in the UK, and got a Samsung Galaxy S for free on an £20 18mo contract without data.
We probably have the smallest operator margins (and/or most network overcapacity) in the EU. The US mobile communication prices seem unbelievable, esp. when everything related to tech is usually considerably more expensive here.