What's the best way to sell my iPhone 3G in the UK?
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.