I was just looking up the rules and found this:
12.Order of Battle: Each House is only permitted to fly six Heavy Battlecuisers and one Dreadnought (Flag ship for the House). All other ships below these hull classes have no restrictions. Restricted ships can be traded in or upgraded to other variants when available. Once destroyed, restricted ships cannot be replaced.
13.House Leaders are responsible for allocating restricted ships and can be transferred between players at the will of the House Leaders. Only House Leaders may authorize such transfers.
I would interpret that as meaning no ships larger than a CC should be available for sale. Yesterday I saw a I-C9K and today a I-B10V in the shipyards.
Actually, the bigger ships still would need to be available in the shipyards at all times.
One of the things the rule, as written, allows me to do is to, on the fly and at my discretion, is reassign my BCHs and DN at will. Theoretically I could log in at 8:00 PM, swipe the DN from her normal pilot, fly it for 2 hours or so, then give it back at the end of my night. Or, I could have elaborite C7 "timesharing" schemes where I keep the C7s online as close to 24 hours per day as possible, and not rely on nutters to do that...
And it's a tradition on test servers that the restricted ships are cheap and free to fly. Here's your chance to get your B11KVXZPQ super-battleship with self-escorting carrier features, minesweeper and commando deck...