Oh lord. It's as if everyone (here, official forums, reddit) has forgotten how the current system works.
Under the new system, Mk XI costs one component that will cost 5k. Mk XII costs one 5k component and one 15k component. That seems to be currently regardless of type: beam array, shield, pulsewave rifle, flow capacitor. I should note that Mk Xs do not currently have any dilithium cost.
Under the current system, Mk IX weapons cost 5 Uncommon Unreplicables and Mk XIs cost 15 - at which were 1,000 dil a pop. Hell, Mk XI shields cost 31 Uncommons, and 75 Commons on top of that (10 dil each, but it adds up).
Yes, a crafter could buy the Unreplicable Mats on the Exchange. From what I understand, though, the components that cost dilithium? They can be put on the Exchange, too.
The actual dilithium sink will be if the crafter is completely impatient and wants to rush completion on non-component crafting. (I have no sympathy for rushers, so that's falling on deaf ears.)
Yep, the new system costs dilithium. But it always did.