In the thread where the person posted the doff costs on tribble they mentioned reqruitment missions and trading up costs dil, so considering the direction they are going I bet trading for lower costs dil too. I'd be suprised if it doesn't.
Playing this for years now the exchange evolves over time. You just need to keep up with the current "hot" thing is now in the past:
Romulan ale and rotgut were going for 300K plus per bottle for the bar-tending mission was out and fleets needed it to move on
Refugees were going for 200-300k per when the DOFF system came online for asylum missions
Tholian reward boxes (not the lock box) went for mad money when they first came out and people wanted the gear in them.
When Diplomacy came out those Jumja sticks went for mad cash b/c people did not want to go to Ds9 to pick them up when they can get them off the exchange.
Uncommon replicables go for 90-100k each b/c people will spend EC on them instead of dilithium.
You just need to pay attention to what is needed/when. There is no tride and true way to earn EC in the game that will last. It's the nature of economy.
I agree only the ones who cant wait have to pay the Prize. Atm there is a raising in Prizes for Doff packs, even the ones from the Lockboxes,so im sure there will be a good fortune to make in the Future.