Marvel 6 Movie Blu-ray Boxset - now £31.49 at Sainsbury's Entertainment (with new customer voucher code)
Now even cheaper!
You need to be a new customer of the Sainsbury's Entertainment website to use this code at checkout: SETENJ12 (code tested and working). New accounts created for existing customer addresses seem to be having their orders cancelled - so unless you use a different address, this is unlikely to work.
The Incredible Hulk
Iron Man 2
You could also use the code on the standard releases of Avengers Assemble, making the Blu-ray £11.69 and the 3D Blu-ray £13.49