IMTU, the only system on a starship that *needs* to be built in a shipyard is the jump drive. If someone can glom onto one of those from some other source (wreck sold for salvage value, lucky find in an asteroid belt, small merchant line bankruptcy sale, etc), the rest of the ship can be built by any competent repair shop. So a lot of the ships in my campaigns - all of which are set on the fringes of settlement - only look like various CT ships (when they do) because using an existing hull (even if it starts out heavily damaged) is easier than building one from scratch.