There are some great looking ship models in there, but they’re doomed as being things like rank 6. Premium ships could be sent through a secret project ship plant to have their ranks adjusted and modules rearranged. This idea is to make premium ships more valuable.
Secret project ships are quite expensive, so I’m sure you’d expect a ship plant to have some expense. Let’s not forget the premium ship already cost some real money, and it was a fully usable ship to begin with. I think it should be easier to convert a premium to an sp than it is to make an sp. Their conversion expense would be relative to the original price tag too since the prices vary on premium ships.
An alternative to being directly resource expensive would be something about gameplay being the route to entering a premium ship into the plant. If the pilot can get their ship to certain far away zones, find the plant, and do without the ship for a while, they can pick it up when it’s done.