Does anyone know how the AI determines the cost of a military alliance? I wonder if it's more than just your unit count and attack strength. One of the things that I'm pretty sure is missing in the equation is the distance of you to the Civ that is the target of the MA. But I was wondering how trade rep, diplomatic standing, tech and your civ's strength compared to the civ you want the MA with, level factor in.
A few gpt is really not worth getting into a war, a nice new tech and a large amount of gpt however.. 

) i got into quite an ok military position by 1000bc. now my only close neighbour managed to get himself into war with 4 (!) sid ai´s. now i was able to get several still missing first tier techs (you know, the old "buying up from behind" game) for free or very cheaply by allying with all 4 opponents. sweet! 