You can always get 50% discount as others have said - I cancel when my discount period is due to expire every year and without fail they eventually call and yield to 50% off quite quickly, at which point I accept. Likelihood is that they'd go further but that might require a few more minutes persuasion.

We've decided to give Now TV boxes a go for next year though, vouchers allowing 12 months of sky movies and 12 months of sky entertainment for the kids disney channels for a total of £100, and the PL and CL football is at no extra cost with our BT broadband.