ok... i try buying a star system from ai, even a class 5 or 6, and even when i give all my techs, money, even ALL of my star systems, they never say yes! so, to see how crazy ai is, i ask for a simple planet, offer then 25, 20 techs, 10000 BC, and all IP, they say no, this is with no influence problems.
then, i offer them a planet. i get under 100bc for mars, and earth won't get me 1,700!
i think this should be changed, but not so that you can kill a civ by buying all they got. mabye the more systems they have, the less value the planets have. if they have 3 planets, it should be almost impossable. and a planet with wonders should be hard to get. a class 26 should be harder then class 5, and capitols require so much that you could just build a super fleet and take it. the reason i want to buy them is to go further away, or even, when im about to loss, i can buy a planet from another race, far away, and try to rebuild there. this would help on a gigantic map.
merry christmas