Can't Buy Venderbight Ship?

I’ve been saving up for a 1000 echo ship sold in the ship-yard at Venderbight, i think it’s called the Leucothea Steam launch. having finally got the money (by way of selling some juicy tidbits to the university) so i sailed up there, but the trade button was grayed out, even though I had nearly 3000 echoes. Why can’t I get it? is it a mission reward or something? Thanks

Is it a potential choice at the end of a storyline.

Yeah, it doesn’t -cost- 1000 echoes - 1000 echoes is how much you’ll get for trading in your current ship. The yacht is earned through completing the First Curator’s quest.