If you've watched the show at all, you know they can do a whole lot with their replicators. Need a meal? A hot drink? Feline food supplement? Go to the replicator, tell it what you want, and off you go! Sure, it can't making living things, and it seems they tone some stuff down (synth-ale doesn't seem to be the "good stuff"), but it seems it can make just about anything.
Star Trek Online's crafting system has two unique crafting materials that bear examining: Common and Uncommon Unreplicatable Materials. Costing 10 and 1,000 Dilithium each, they represent something that can't simply be ordered up on demand. As such, they represent an obstacle to crafters because the players must earn Dilithium to buy them, buy Dilithium with Zen to buy them, or have someone else get it for them.
Or, one can simply look on the Exchange. Yes, it does seem like they're one of those great things that can be bought and sold instead of being character/account bound. As such, they're compatible with my goal of earning Energy Credits.
At 10 Dilithium, its safe to say that Common Unreplicatable Materials represent not only a pittance of time invested (two DOFF missions will reward that), but are also a fraction of a cent at current Zen:Dilithium pricing (1 Zen = $0.01). Prices for them seem to start at 28,000 EC per unit, with batches of ten seeming to sell for a more reasonable looking 100k EC (10k each).
1,000 Dilithium will get you a lone Uncommon Unreplicatable Material. Those seem to start at 190k and go on from there. The high 240k mark seems to be a bit more common, though.
The Z:D exchange rate has been 1:15x for a while now, so 1 Zen will get enough Dilithium to buy 15 Commons. I personally prefer to sell on the lower side, so I'll be pricing 10k each, giving me 150k in potential sales. So, 6 Zen worth of Dilithium may actually garner me 900k EC. This is absurdly good compared to the other methods I've been looking at! However, the question is "how long will it take to sell everything?"
Going with the Uncommons? Well, 1,000 Dilithium would buy 100 Commons. At 10k per common, that's a cool million worth of Commons. If a single Uncommon only garners 240k, it seems like you've got better places to put your Dilithium if you're looking for EC. That said, again, one must figure in supply and demand - virtually anyone can earn enough Dilithium to buy the Commons with no problem. The Uncommons would take more time, and you're really at the point where its not a trivial matter. Whereas a Common is a fraction of a Zen, an Uncommon could be about 7 Zen. That's a lot of Dilithium, relatively speaking, and I'd rather save that Zen:Dilithium for larger things.
Moreover, if you go with STOwiki.org, it seems that while the two are used for high-end crafting, that's about it. Its of limited use, and one has to wonder how fast-moving a crafting resource will sell.
As an experiment, I've bought 10 Commons, and put them up in five single units, and one 5-unit lots. Each is priced according to 1 unit = 10k EC. So, hopefully we'll see soon! As such, right now I can certainly say, "keep you eye on it," but I'm not sure if their primary use (crafting) is popular enough, nor if the Dilithium prices are such that buying them with Energy Credits is more attractive or not. We'll see!