Hi - Decided to post this in misc as it is dependant on what kind of phone you have.
I received an e-mail from the Carphone Warehouse last Friday which said that they were offering cashback on old mobiles. Ok so this has probably been going on for ages but it's something that I wasn't aware of.
Anyway - I put my phones (Nokia N82 - 2 yrs old) into the website and discovered that it was worth £90. I have been thinking about purchasing an I-phone 3GS but the phone purchase price has been putting me off (£125 min). I off set the £90 cashback against an I-phone meaning that it only cost me £35. I went for one of the lower tarrifs as I'm not a heavy user so I got 150mins, 250 texts and unlimited 3G access for £30 / month with Orange on a 24 month contract. Ok not for everyone but this is a great plan for me. It also helped me keep the cost of the I-phone down. Hope some other will find this useful