The value of an AI's planet was 'tweaked; a few updates back. These days the AI's will not sell you one of their planets. The only way to get them from the diplo screen is during warfare & you petition for a peace treaty, if you have sufficient power you ca demand planets as part of the treaty.

Thank goodness they haven't nerfed buying ships from other civs: when playing under blind exploration conditions, I like to buy a scout or other cheap ship from each of the other civs so that I know in general where their planets are. I don't think the AI is smart enough to follow those scouts back to my territory, although I generally don't play at the more difficult settings.

It is still too easy to buy planets off the AIs though

For reasons stated above, I have not found that to be the case.

I want to be able to trade planets especially ones near my border and I want to be able to trade and purchase starbases.

You still can, no-one has taken away the ability to trade for planets or starbases etc. Only their values to the AI were changed to make them far more reasonable and less exploitable within the context of the game.

Becuase really all I want to do is trade the AIs Starbase Mining Research 49 in my territory for my Starbase Mining Research 132 in there territory.

Never tried it, so can't say for sure, but I doubt it is possible in the current version. It usually costs 2.5-3million BC to buy a fully upgraded mining starbase now - can't say I've ever even considered selling or trading one away, so no idea what the AI would give for them.

I agree that in that type of situation (assuming both SBs are at the same upgrade level), an equal trade should be possible. Maybe the value that the AI attaches to player-owned starbases needs to be revised and brought into line with the value it assigns to it's own. That said, I'd happily give up 4 research resources for one military or economic (especially after I've completed the tech tree) - so maybe even that is still exploitable to a certain extent.

I would still be against planet for planet trades though, because it really would be too easy for a human player to exploit. I think writing AI code to get round that exploitation, while possible, would result in a huge performance hit.

I am for equal trades ony. If I want to trade the Ai for a PQ 10 for a PQ 10 I should be able to.

Yes - but is a PQ10 with a 300% production bonus tile equal to a PQ10 with a 300% research bonus tile, or 3 100% influence bonus tiles etc? Did the planet receive a bonus or penalty on colonisation? How well developed is it, and how many people? Does it provide enough influence on it's own to overcome the influence of planets in surrounding systems or is it going to flip back to it's previous owner?

All variables that would need to be analysed in AI code to determine the equality of the trade in order to avoid exploitation.

Yes - but is a PQ10 with a 300% production bonus tile equal to a PQ10 with a 300% research bonus tile, or 3 100% influence bonus tiles etc? Did the planet receive a bonus or penalty on colonisation? How well developed is it, and how many people? Does it provide enough influence on it's own to overcome the influence of planets in surrounding systems or is it going to flip back to it's previous owner? All variables that would need to be analysed in AI code to determine the equality of the trade in order to avoid exploitation.

I seriously doubt that is how they program things now. Simple way a PQ 10 is a PQ 10 period. Bonues don't count or any of that. You are making it WAY overcomplicated.

And I do not think that is how they program that. I seriously doubt it. Your giving them way to much credit.

These are people who remove things from the game if the AI can't use it. I mean come on you think they program that in depth? Well if they do I never want to hear another, The AI can't use it excuse again. Because if they program it that complicated: I never want to hear that AI can't use it excuse again.

That's one way to do it. Buying planets doesn't risk the kind of military retaliation that taking one by force does, especially if you are trying to take the wealth path to an Influence victory. And if you're rich enough, you can just buy AI fleets before war is declared, then salvage the combat ships for cash, and convert the troopships into warm bodies for your colonies and use the scouts you buy to explore.