Cost-based pricing would say that digital media streamed to the home should always be less expensive than the same media delivered on physical disks in boxes delivered by UPS.
Value-based pricing says that someone with a Roku who wants to see a show right now, not two days from now, and doesn't have a DVD player and doesn't want to hassle with putting disks in and out to get through a whole season of a TV show might pay more for the digital delivery.
Sometimes cost-based pricing rules. Sometimes value-based pricing dominates. Sometimes pricing is weird due to temporary scarcity or gluts. Sometimes pricing is inexplicable. Which is this (click to enlarge):
Entire Season on physical DVD's with free Amazon Prime delivery: $13.99
Entire Season streamed digitally: $22.99
Since I like to buy the disks and then rip them to my video server at home running XBMC, I was happy to get the disks inexpensively.