They are not comparable. Pressed dual layered Blu-ray Discs (BDs) are cheaper to make at the moment than the recordable or rewritable dual layered BDs.
Well, that wasn't what I was implying. I was wondering the following: price of recordable double layer BD == ~2.3 * price of recordable single layer BD. Could that imply that price of pressed double layer BD is also > 2 * price of pressed single layer BD?
I'm not sure about the actual costs.
The only thing I do know is what David Williams said at one of the cons. According to him, a pressed dual-layered BD is cheaper than 2 pressed single-layered BDs, but there is a price difference between a single-layered BD and a dual-layered BD. Unlike DVDs were the cost between the two is nonexistent.
It's cheaper to have 12-13 episodes on one dual layered BD and one single layered BD, than on two dual layered BDs.