I like the idea of small, functional, cheap vessels that can hold a relatively small amount of cargo but get a player 'started' after some time in the setting. They can use those ships as a stepping stone to earn more money practically for larger vessels. So keep the entry low, but make the larger vessels perhaps more expensive.
That being said, not too many characters have tens of millions of KS to dedicate to a single large ship even after a decade of RP. I worry we'll overcompensate and go too far the other way with this in the name of realism. If we went that route, we could go from "we can make matter and laborers, this costs little" to "this is the mass of an aircraft carrier and is more advanced, so it costs the same or more" and everything in between.