In reply to Toby_W:
Erm no they don't! Chain reaction and wiggle are often more expensive than as suggested Merlin, who I've had great customer service from.
The key to chain reaction or wiggle is to have a discount code to use with a purchase as well as quidco or topcashback.
Ribble, Probikekit, sigma all offer competitive pricing too.
Sometimes Westbrook have some good deals as well.
Some of them offer cash back with quidco or tcb too.
As Andy put above £300 gets you 105.
Now if you can find me di2 (upgrade kit) ten speed for less than £500 I will be impressed