there could be a kind of supply/demand system in place, if one suit is used a lot, the price goes up, while other suits that arent used much go down in price, same with weapons. This would balance prices and create more unique gameplay.
I like this suggestion tho

Could be a case of the longer the nuke goes on the price goes up, as defenders defences are slowly being depleted it would make for somewhat decent balance. As long as prices aren't hitting silly levels per use so people don't even bother!