Phones4U have the refurbished LG KG800 "Chocolate Phone" on o2 Pay As You Go available on their website for just £139.95. Purchase via QuidCo.com and you'll get £5 cashback, bringing the effective phone cost down to just £134.95.
The LG KG800 is a smooth, slider phone and looks like a chocolate bar. The external keys are actually invisible, they light up red when ready to use. It has 128 MB internal memory with an MP3 player and MPEG4 video player. The KG800 also has Bluetooth and a 1.3 megapixel camera with flash and video record.