It seems that at least some part of the reward formula is manually set by the devs. If you have ever used Shiva C, then you should know how extremely low the reward it. Once I have FBomber a NCat and Timberwolf that were standing way too close to each other. They both were in "orange" armour zone before. I killed both (of the most expensive mechs in a game) with one pass, scoring 60k CBills! 30k for a clan uber! Usually, raping some Assault with Shiva C gives you only 30-40 k, sometimes less. Just barely enough to repair the damage and get more bombs.