Since the AI's haven't got alphabet yet you can probably do writing @ min and sell it around before the others get it.
Apart from that I wouldn't spend money on a tech unless you think you can buy from one and sell to the other, but as you say, it will be devalued by when you purchase it, and you pay the 50% tech lead penalty if you buy a tech that only one has. All in all, brokering with just 2 civs is nigh on impossible. Much better to get a tech no-one has and buy them all @ miser.
__________________
<b>Calculate the probability of culture flips: Flip Calc</b>
|