I found this cheapest in today's date. At black friday it was £279 without any extra tools.
This model comes with the benefit of additional tools compared with the standard DC75 Cinetic Big Ball model. These include:
Tangle Free Turbine Tool
Up Top Tool
Carbon Fibre Soft Dusting brush / Reach Under Tool.
Also quidco offering 4.95% Cashback = £14.10
Effective cost = £284.99 - 14.10 = £270.89 (Free Delivery)
Currys & John Lewis still charging £499 for this model (without any extra tools).