Let the hive mind of Engadget get that for you.
"I own an iPhone 3G and I'm looking for a decent speaker / alarm clock for it. I am going to listen music in a mid-sized room, so I want nice quality speakers with solid bass. I also want to use it as an alarm clock, so it would be great if there is such a feature. The price can be low-mid to mid-high range. I was looking at the Klipsch iGroove SXT; it's powerful, slick and the reviews are good, but it doesn't have an alarm clock feature. It's no deal breaker if I can set it up from the iPhone, but I'm not sure. Thanks!"
2 year contract: Fone=$450 Bill=45*24=1080, total=1530/24=$63.75 per month
1 year contract: Fone=$500 Bill=45*12=540, total=1040/12=$86.66 per month
Off contract: Fone=$550 Bill=45*12=540, total=1040/12=$91 per month
(assumption: without contract you keep the fone for a year)
So the longer you stay the cheaper the fone and the relation becomes, although logically there shud be a much cheaper V+D plan for off contract buyers since they are paying a premium for a device.