Kinect seems to have dropped in price again at CEX, and you can now get one for just £45!!! (EDIT: Has risen to £48 since the time of posting, CEX prices have a habit of doing this). This is a great deal for 360 Slim owners, as they don't need the PSU. Everyone else can get the PSU included for another tenner (although I'm going to investigate and see if I can find them cheaper elsewhere.) With Internet Explorer coming this Autumn (already available for those in the dashboard beta) along with the apps already available for Kinect use, it's a good time to pick one up cheap!
This price is in-store. Add £2.50 for delivery.
*** Third-party PSU on Amazon for £6.89 delivered: http://www.amazon.co.uk/XBOX-KINECT-SENSOR-POWER-SUPPLY/dp/B004ULYCVS***
Please let me know if you find one cheaper so I can add it to the post :)
*** £5.49 on eBay: http://www.ebay.co.uk/itm/UK-Plug-Power-Supply-Charger-for-Xbox-360-Kinect-Sensor-/320785299699?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4ab04b38f3#ht_999wt_1396 ***