First of all, congrats on your winning game, and I'm glad you're enjoying CIv3 again!
I'm a little bit curious about this:
"if an AI cannot quite offer market value for a tech I am selling, I often simply give the AI money, which I will get back anyway once I sell the tech."
You're saying that instead of selling a tech for below market value, you give the AI gold, then sell the tech to them at full price? Outside of Wall Street, I can't see the advantage to that over simply selling the tech at below-market price if you are going to sell it. Sure, giving the money away helps your reputation, but so does selling tech at low prices.
I can't personally see the benefit of doing it that way, but then again I like to do things like making sure the negotiating table has been cleared before saying good bye to the AI if I'm not making a trade. The only difference is that I know
my method doesn't have any in-game value at all. :P