Walked into WH Smith @ Ipswich, noticed this on the shelf. Not been advertised and deifnitely not a mis-price as I checked. Great price for 3 films and another blu ray of extras! Will upload pic of receipt when i next sync my phone :)
Forgot to add that when I brought it, i got a card aswell that if you present between 13th and 26th April, you can get 10% off Media, and 20% off Books. Be a great bargain if someone else gets this for £18!!
EDIT: Now confirmed in Bedford, Trafford and Ipswich, so definitely not a mis-price!