Starships are not mass produced like Lasguns. Each one is a unique vessel crafted from the ground up. Many take centuries to construct and require thousands of tech priests and countless laborers to build. While it can be said that they fall into general classifications in regards to their size and capacity, no two starships are exactly alike.
Also, while Warp influence is strictly prohibited, the warrant of trade allows some rogue traders to incorporate xenos technology and artifacts into their ships (see FFG's Rogue Trader)
Also, while Warp influence is strictly prohibited, the warrant of trade allows some rogue traders to incorporate xenos technology and artifacts into their ships (see FFG's Rogue Trader)