i like the monatary cost of implementation idea, i think it would put a break on the super fast spread of techs across the world. it just always seems odd to me that civs that hate me, and are supposed ot hate each other, all end up sleeping in the same technology bed together.
my thoughts on the matter are along those lines. I think tech trading is a needed component of the game, i mean who hasn't tried to turtle up and then had to sell everything in order to get weapons no?
(1) problem is that when you try to focus on one area and spend considerable time developing it, you get scrwed in that others have developed a wide range of techs, which is fine...
(2) but every game where i have tried to make sure i get a good number of base techs to keep up with the jones, all of a sudden i find that the AI has not only got all the base techs i have but has also managed to somehow specliaze in an area as well.
the solution to (1) is kinda easy, i think at least. perhaps the cost of implementation shoudl come with a tech research penalty, for example if you are researching lasers and you trade for a mass driver, you take a hit on your research for the lasers. concept being that your labs are tuned for research in a specific area and that the new tech requires some analysis, thus resulting in a penalty for the research. you could also make this penalty stack, so the longer you focus in an area, the more ht you take when you have to go try to implement other techs that you've traded for. that would seem to slow down the advance of (1), at least somewhat.
(2) poses a bigger problem since you already get penalized for being a generalist in terms of research cost, so a double penalty wouldn't seem fair, esp if you are being general so as to incorporate many different techs in your labs. perhaps a tech lvl limit to the transfers would solve the problem? so that way you can go out and buy a lvl 5 phasor when you don't even have beam weapon theory? that would force you into remaining general however.
just some thoughts