Why are dvds included in almost all Blu-ray releases?

[raven007]

Originally Posted by Kryptonic

Really? Getting a 4-disc 3D combo of Avengers or Prometheus (w/ U&S) for $19.99 is too expensive? Get out.

some stores have the combo packs for like 24 or 30 dollars where a blu ray only is sometimes 20 and the dvd is sometimes 16 look at the katy perry movie that came out the dvd was $12 the blu ray with the dvd was $16 and the 3d blu ray with regular dvd and regular blu ray was $24 so your paying a little more for blu ray combo pack at least i think