Hey, exo costs are more balanced then I thought; just a few blatant outliers.
In general, the AI pays a little too much for Guardians and Riot Starships, and too little for other starships, but it's probably within the tolerances of the exo tiering system.
(Made with 7.0. When looking at the chart, bear in mind that it's logarithmic, so differences from the trendline mean more per pixel the further you go up.)
EDIT: Okay, going over the numbers, it's not actually that balanced (though the effects aren't really noticeable in actual games for the most part). Assuming the Strength value is a reliable estimate, perhaps running a script to reassign ships to exo tiers based on it is in order?