I have to agree that the demand issue is a major factor. They just issued the first season of Relic Hunter - 6 DVD set - for $17. But the most recent season of Mad Men was $55. Merlin is not considered a going concern in North America -- hell, we should consider ourselves lucky they even bothered releasing it at all here after the thud it landed with on NBC -- so they lowered the price to make blind-buys more attractive since most consumers in North America will not have seen it. Doctor Who has a bigger fan base, so therefore it's not expected to draw the same "blind buy" purchases, so they can up the cost.