It is time for my contract upgrade and so I called Vodafone asking for the HTC Desire. After haggling they offered me £20 per month for:
Unlimited internet (fair usage 500mb)
24 month contract
The catch was that they wanted £108 for the phone. They then asked what old handset I had (a Nokia 5800) and they offered to buy that back from me for £68 regardless of its condition. They just send a jiffy bag which is all guarenteed in the post by Vodafone.
The net effect is the Desire will cost me £21.66 per month which I thought very reasonable.