I think that the current system of buying capital ships from the BBS is fine ( but then I would - I've just bought a Teladi Condor that I'm using hull repair technology to patch up
).
I had a similar idea, but didn't know nearly enough about scripting to be able to knock a script together. My idea was that rogue Teladi salvagers would jump into battle zones after the fighting had finished and use their TLs / tugs to pick up any ships that had been abandoned. Mostly, they'd deal in fighter ships selling to dodgy organisations that didn't have the governmental contacts to buy them legitimately. Occasionally they'd offer capital ships, but any captured carrier or destroyer would have been so shot up that the crew would have had to bail. The salvagers would be willing to sell them to you, but wouldn't bother repairing them first.
I was considering putting the idea on the forum as a script request, but now I don't have to. Thanks Cycrow!
I do take the point that buying capital ships is maybe too easy. I personally don't feel guilty about buying my Condor, as I have pretty good race relations already - just one rank below being able to buy capital ships from shipyards (for all races). Increasing rank is so slow now - even a Xenon invasion will only increase my rep by 2% or so, and I can't even leave the game on SETA because I still have issues with freezing! Maybe there should be something extra involved, though - the peeved former owners of your new ship could send out a squad of fighters to destroy it and/or you. Imagine a dozen argon novas armed with mass drivers suddenly turning red when they get within 1 km of you!