Nokia Lumia 800 Unlocked £159.99 plus £10 PAYG top up price match in store at Carphone Warehouse £169.99
Price match for Orange deal - Nokia Lumia 800 in store on PAYG for £159.99 with £15 top up required:
Carphone Warehouse will price match Orange BUT their handsets are unlocked whereas Orange's are locked, and they only require a £10 top up. Thanks to Adidas Addict for the suggestion in the thread above!
To get the price match I had to show proof of the Orange price - I took a photo of the Orange store display.