got at some point less than zero money after an upgrade. dont know, what i have done.
very nice game, i wish i could upgrade the parts seperatly and experiment which combination pays off best way. please put in some difficultys, that a upgraded machine is not repaired to 100% could be one obstacle.
Would be a good idea but we want to focus on new content first (weapons and maps). For now you'll have to test this on your enemy :)