Maybe not double for new releases, but for the vast majority for catalog titles triple may be more inline in many cases.
Underworld-Evolution (Widescreen) : DVD : Kate Beckinsale : Bill Nighy : Scott Speedman : Len Wiseman : Sony Pictures - Buy.com $9.66
Underworld-Evolution (Blu-ray) : : Kate Beckinsale : Bill Nighy : Scott Speedman : Len Wiseman : Sony Pictures - Buy.com $35.05
There were many more cases like this.
You are quoting a DeepDiscount DVD price against buy.com's price. Note that for some reason buy.com (which I have used for years) is not offering the best Blu-ray prices. Amazon.com, for example, has it for 19.95 (all right they have the dvd even cheaper than buy.com). I also saw it back during the bogo days under $10 for the BD.
For new releases the MSRP and street prices for DVD vs BD are much closer than this example.