You can buy a retired military jet if you can afford it, or a tank. But they won't shoot.
It took 3.5 years to fix the sub so it could last another 20? Or worse yet, only 16.5 if the 3.5 are included. Seems like a lot of time and money spent to me. Maybe it's just a cover story.
Good luck building and programming your own launch system and buying or building the missiles for it.