It seems like I can barely sell a ship for its production cost, even a decently equipped warship to a race with tons of money, a bad military and low technology. But here's something different that might really need pointed out:

Civilization alliances seem weak and thin to me, even on GC2... I think this would be an excellent incentive to strengthen alliances (and apply some considerable pressure to break up the alliances of other civs!).

Initiate a trade with an ally. Click any ship design (on your screen or its screen), specify the number of ships (they can be just a current design the civ can build, not just complete vessels), and click something on the other side which you feel is worth the number of ships (such as a technology, or a bunch of cash). When the trade's accepted, no one gets anything, yet...

Now that civ can produce the ships, and once one or all of the ships reach the ship-trade rally point or are otherwise handed over, the civ who built the ships recieves a *portion* of the payment, such as a technology is researched to a certain percent depending on the worth of the given ships.

I think this could be interesting, for allowing specialized civilizations to remain competant in other areas -- but only with close friends. It's mostly foolproof, although it can be backed out of (the seller takes too long and the design becomes obsolete, or the buyer could just run out of cash). It's not that different from direct, immediately effective trades, but... imagine the micro-management of it... It'd be like taking out those loaned purchases. Maybe the same thing could be done for social production, or, or..

The obvious problem would be balancing this with the AI -- what ships does it need to buy or what guns it needs to hock for a quick tech or wad of dough, or to know if it's been buying scrap heaps for the last 100 turns. Whether you want an equalizer this potentially strong in a game like GC2, and badly enough to debug it, I don't know...