Just how rare are Royal Shipyard Plans?

[Willy OneBlood]

It's basically a recipie to produce a large master shipyard for 25K Dbl. Seems to be terribly rare, but I have no idea. I play on Blackbeard mostly, and i'm wondering what kinda value these have. Also any suggestions i.e. learn it and sell shipyard deeds or sell the recipie - i'm jus trying to guage if ppl are actually trying to manufacture these monster ships or not. |3y the way i'll sell 'em for 1mil Dbl; then i go to the gold sellers an trade it for a RL house.