A few weeks ago I was playing and was assaulting Bismark in mid game. I eventually ran out of steam and had to make him a vassel. He had three marginal cities left. I was running really low on cash and was checking the trade table constantly. Every three turns or so I would look over and see that he had 12 gold, 10 gold, 11 gold for trade. You would think that someone with such a puny civ wouldn't have money to burn, but I ended up having him on the line for about 55 Gold worth of resources. That was pretty awesome. Obviously I didn't get up to your total amount, but I was pretty excited at the time.