I've noticed that they value some techs over others, not just weapons... Anything that gives trade or diplomacy bonuses... Conversely, they don't give a damn about Sensor techs.
One thing that irks me about the trade window is: say I have 4 techs I want to trade for X amount of BC... if I trade them all at once, I'll get significantly less BC in the end than if I traded those techs for BC individually. But that's not what irks me... What gets to me is manipulating that damn money slider, and the different arrow buttons for tens and ones... 4 times in a row... for each race.
It should just automatically put the maximum amount in there for me, really... I don't really need that kind of "immersion" factor to adjust that slider and the arrows each time. I know they're adding in arrow buttons for 100's in an upcoming patch, but it's still tedious.