The actual phone is £99.99 with the discount code PAYASYOUGO10 the price come down to £89.99. You can also trade in an old phone and get another £10 off bringing the price down to £79.99.
I think you can use quidco for further discount.
Model SONY ERICSSON K800i
Cyber-shot camera phone
3.2 megapixel camera
3G video calling
Video capture & playback
External memory slot
Battery Standby Time Up to 350 hours
Battery Talktime Up to 420 minutes