I've got an iphone - its an awesome phone, surpasses anything I've had before
I bought it from o2 for £269 on their website via quidco.com - which gets you £35 cashback.
Once you get the phone unlock it - takes 5 minutes, don't bother signing up to the iphone contract.
Then sign up on e2save.com for a 12 month free (when you send the cashback) contract, which came with a Nokia 6300 - that I sold on for £75.
Bit complicated but at the end of this I get an iphone for £159 with a years contract free (once the cashback cheques come mind).