I like this idea. I've lost track of how many times mixers have firebombed Gold, the mess is instantly cleaned up, and any RP that comes of it becomes a simple "whodunnit", which, if we're being honest, oocly we already know who done it, usually. So the RP never deviates from the connect-the-dots type of investigation that gets passed on to CorpSec which ends with the same players involved in the RP over and over even if others try to get involved. This would create -consequences- that could overlap different styles of play and lead to more interesting stories, imo. Consequences are a fixture in CP storytelling. We need more of them.
That said, not sure it should be cost-related, but also not sure what could replace that. Bombing a business on Gold would have different consequences than bombing a building on Red. Bombing a building on Red might hinder business, even shut it down temporarily like what was suggested. Bombing one on Gold might mean installing checkpoint security, more brazen corpsec authority to harass mixers on Gold near places of business, heightened internal scrutiny and paranoia. TOugher Judge presence. Real Dredd style. I don't know. Anything that helps push a narrative other than the usual lets go kidnap this mixer and make them do things.