It's not only the tech trading that is exploitable. Basically, anything in the diplomacy area is ridiculously overpriced. I rarely go into the diplomacy window since it is useless to even try to negotiate anything.
You can sell disputable mining bases for around the price of 1,000,000 or more. Remember that these bases only cost a few thousand credits to build. Also, they will never bring back even close to 1,000,000 credits in resources.
I've seen races willing to give me more than 3,000,000 to enter into a war they were in. Credit wise, think about how many ships you can buy with that! If it's in the beginning of the game, you could create massive fleets and completely wipe the other AI out with it.
Techs themselves are highly overpriced, just in general.
It goes the other way as well. Trying to negotiate a peace treaty is useless. In my last game, the AI wanted me to give them more than 1,000,000 to stop a war at the very beginning of the game. If I had 1,000,000 credits, I could have taken over his entire empire
As has been stated, the diplomacy area in this game is one which really could use massive changes. In my opinion, everything is overpriced about 5x - 10x what they should be.
< Message edited by MartialDoctor -- 6/16/2014 4:20:25 AM >