Children's Toys. That explains it. I never started that chain because the Jevonite and Shapeshifting Lockets cannot be obtained except by opening lockboxes or paying insane amounts on the Exchange.
There are haggle missions for them in Cardassian space, or there's the fleet bank, which I usually use since I feel that I'm putting in enough other stuff to take those 6 things out. That's why it's there.
Or, again, the exchange, which I use as well ... certainly no more than 100K for all 3 of the Jevonite and 3 of the Shapeshifting Lockets and just the Rare Alient Artifact you get from it is worth much, much more than that.