Hey, thanks for the comments, gknoy. Some good ideas there, a number of which others have mentioned before but you expanded on them. However, frankly, I just don't see a sub being hijacked without inside help - ie. having subverted crew or moles on board. Once you have someone on board helping you, it's a much easier proposition.
Actually, I think an attack sub is an excellent platform to launch attacks against land targets. To me, it's the perfect match between stealth and attack capability.
The reason why I'd prefer to steal a sub rather than buy one is that it
does work out cheaper to steal than to buy one. Stealing also avoids the obvious paper trail to a buyer, and lastly, a bunch of runners like ourselves would never be able to obtain permission to buy such a vessel (and no manufacturer would be able to obtain sanction to sell one to us).
I thought about hacking the manufacturer's order list (that's how our group managed to get our hands on certain restricted items without obtaining the permits for them) but there's a big difference between taking delivery of, say, a consignment of milispec armour with forged documents and taking delivery of a submarine.
It's a lot easier to disappear with milispec armour than it is to do so with a sub in such circumstances.