Play.com have this for 129.99 while PC World sell it for £164.99 in store.
Use their pricematch policy, bring the page up on your mobile while in store or print a copy of their price promise and the play.com page and go to a PC World store.
Pick up the drive and go to checkout.
Present the page to the checkout operator and ask them (nicely) if they can price match this for you.
Make sure they deduct 110% of the price difference and not 100%
You should pay no more than £126.49 for this 1TB NAS drive.
I have done price matches at various PC World stores and never had any problems.
Read up on the device though as WD don't seem to get a lot of good press on their HDD's.
I've bought one today so will post a review when I've got this going, any feedback on these will be appreciated too.