The 3 for $20 deal is a steal... Build 2 more for the sake of the discount. I'm guessing too many were just doing one and they're trying to move volumes of parts?
Maybe they are indeed going to phase this out? I hope not (not that it should matter to me, as I don't go to either park really). I dig them and think it's a neat, unique experience for people who do go.
I really wish I had a 2nd Starspeeder "playset" (of which the one I do have, is among my fav pieces!).