I must agree with the assessment of most others here. This is much too detailed for SE. We can't even choose which treaty conditions we want to grant yet (trade alliance, use of resupply depots, intelligence point sharing, etc.) -- we have to stick with a fixed list of set treaty types. And you want to deal in specific trade goods??? Not likely.
This could be added in a more generic form, though. Like this: Have a new facility ability called "Consumer manufacturing" that increases your trade benefits slightly. Maybe 1 percent. Then, you could have a facility that appears in a special tech area (maybe one restricted to a certain class of empire, the more 'democratic' sort that allows consumer decadence...

). This would provide a way to alter your trade abilities within the game instead of being stuck with the setting you chose at setup. But this is a very GENERIC angle, as you can no doubt see. No specific trade goods are accounted for. This ability represents all sorts of consumer goods in a single feature. Done this way, it wouldn't be too much trouble. MOO II had 'trade goods' for your excess capacity, after all...
A racial ability called 'Consumer Culture' might be an amusing addition to the list with Propulsion Experts and Hardy Industrialists and whatnot...
[This message has been edited by Baron Munchausen (edited 10 September 2001).]