The way I worked it out for the Shravana Hive was, they have a small, weak economy and live in an asteroid belt, so they're much poorer per-capita than an industrial nation on a habitable planet would be. Still, they do have significant resources, and their technology is only a few years behind other Freespacers, who are still relatively advanced (comparable to Nepleslia, if nowhere near Yamatai's levels.)
So, ultimately I worked out that their per capita income should be at least $40,000, not too shabby but certainly not wealthy. Multiplied by the population that's a GNP of about half a billion, which sounds about right. I suspect the planet of Yamatai would beat that by about a quadrillion, let alone the rest of the empire, so it's probably more useful to think about making smaller interactions.