What's the best way to sell my iPhone 3G in the UK? The same as this question ( http://gadgets.stackexchange.com/questions/9/what-do-i-need-to-do-to-sell-my-iphone-3gs ) except with the UK in mind.

I have a 16GB iPhone 3G and have recently upgraded (we don't need to argue if it's an upgrade :p) to the iPhone 4. What's the recommended way to sell it in the UK? It has one small crack on the back near the vibration switch so it probably doesn't count as near new (depending on your definition of near).
The lowest hassle way is probably via one of these "phone recycling" sites.  eg:


Mazuma Mobile (offering £172 or £189.20 in Argos
vouchers currently)
Envirophone (offering £160 currently)
FoneBank (offering £161 currently)


It might not be the best deal on offer, but it's easy.  I sold an old (though much cheaper) handset via Mazuma recently with no problems.