New release today - Skyline is £9.99 on DVD and £12.99 on Blu-ray instore at Sainsbury's.
From what I can see this is cheaper than anywhere online for either version, by the best part of £2. Lots of online stores don't seem to have it in stock either.
It's a pretty "switch your brain off" film. I guess this is where people vote on whether they liked the film rather than the price?!