Just returned from Sainsburys. In the Sales section (standard in most stores) is a range of box sets in all genres at £10.
This box set includes 6 movies:
X-Men 3 The Last Stand
Daredevil - Directors Cut
That's £1.67 per movie! The box set retails at £30.99 at Play.com and £36.99 at CDWOW.com. That's a saving of at least £20.
The store manager confirmed that these box sets are offered in store nationwide. Though this probably means the larger stores.
Other £10 box sets included:
Rogers & Hammerstein Musicals (x6)
Steve McQueen Greatest Movies (x6)
John Wayne Greatest Movies (x6)
Plus numerous others such as: Family Guy, Simpsons, American Dad etc.