A ship with a Freighter hull (Cost 13) with a Small Thorium Reactor (Cost 13) is going to have a combined cost of 14, no matter what other components the ship has as long as the individual cost of the extra components is less than 13 ?

Is this correct ?

The examples in the core rules does not cover combining purchases of items of different costs, and the example ship costs in “Shiny” seems to indicate this.

Cheers, Chris

This is correct! The lower costs components basically have negligible cost compared to those two cost 13 components.