It's a little frustrating at the moment, because we don't know yet how final these tech trees are. I found the same thing about econ starbase upgrades with the Iconians. They get a line of trade boost upgrades (when researched) for the zone of effect, but no production upgrades past the first one. I traded for the next level starbase production upgrade from the Terrans in my last game. It came with the first level of traditional factory tech, IIRC. But I'd have to trade/buy each successive one as an alien tech (they don't link to future upgrades), and it just wasn't worth it to go further. By that time, I was getting a handle on the unique Iconian factory buildings... refineries, etc, and didn't need any additional starbase econ boost to win the game.
So I still don't know if this lack of starbase upgrades is just half-finished, or intentional so we'll have to learn how to run each race differently, or pay through the nose to get additional tech from other races. Actually I like the challenge of using just the main racial techs. As long as I don't go above Tough level where the AI has econ bonuses, I haven't had any huge problems so far... well, except for the very slow Drath start.
